Library of Multiple-Choice Questions for the 3rd test.                ASTR1010



1.
Mars is best viewed from Earth when it is at opposition, but some occasions are more favorable than others. Why is this?
A.
Mars has an elliptical orbit, and favorable oppositions occur when Mars is at perihelion in its orbit and hence closest to Earth.
B.
Mars has an elliptical orbit, and favorable oppositions occur when Mars is at aphelion in its orbit and hence closest to Earth.
C.
Mars's orbit is inclined at a significant angle to the ecliptic, so favorable oppositions occur when it is crossing the ecliptic plane while at opposition.
D.
Even though Mars moves in a circular orbit, the orbit of Earth is elliptical and so favorable oppositions occur when Earth is at perihelion.


2.
Only the few largest asteroids are found to be spherical. Why is this?
A.
Repeated collisions with other asteroids have worn them down to spheres.
B.
Self-gravity for the most massive asteroids was sufficient to pull them to this shape during their early history.
C.
Their visible outer atmospheres assume a spherical shape even though their surfaces are irregular.
D.
They solidified from spherical gas clouds in their early history and retained this shape.


3.
Which planetary satellites are known to have plumes of gas escaping through their surfaces?
A.
Europa and Oberon
B.
Ganymede and Umbriel
C.
Io and Triton
D.
Io and Callisto


4.
What causes the banded structure on Jupiter's visible “surface”?
A.
an underlying rising and falling convection pattern, stretched into bands by Jupiter's rapid rotation
B.
an underlying north-south flow pattern, stretched into bands by Jupiter's rapid rotation
C.
the “sweeping” of Jupiter's clouds through magnetic field lines from Jupiter's magnetosphere
D.
the breakup of strong eastward flows, due to Jupiter's rapid rotation by underlying mountain ranges


5.
Stony-iron meteorites are believed to
A.
have been ejected by volcanoes on Mars.
B.
originate from undifferentiated asteroids (same composition throughout).
C.
be pieces of primordial Solar System material, unaltered since the Solar System formed.
D.
originate from differentiated asteroids (in which iron sank to the center).


6.
Widmanstätten patterns uniquely identify samples as iron meteorites. Why is this?
A.
These patterns require iridium, which is common in iron meteorites but is rare on Earth.
B.
Widmanstätten patterns are radioactive.
C.
These patterns involve crystals, which only form after millions of years of slow cooling.
D.
These patterns are actually cracks in the structure of the meteorite that form only when an iron meteorite becomes heated during its passage through Earth's atmosphere.


7.
Venus and Earth are about the same size, yet they have only one of the following characteristics in common. Which one?
A.
evidence of planet-wide plate tectonics
B.
volcanic activity
C.
a planet-wide magnetic field
D.
an atmosphere made up predominantly of greenhouse gases


8.
The initial and very rapid recession of the edge of the white polar cap region toward the poles in springtime is caused by
A.
the melting and evaporation of CO2 ice.
B.
the increased growth of vegetation toward the poles from mid-latitudes.
C.
the change in color of the rocks by photochemical action, similar to bleaching.
D.
the melting of H2O ice and subsequent runoff of water.


9.
Where in the universe would you look for Ganymede?
A.
near Jupiter, because it is one of Jupiter's moons
B.
around the planet Mars, because it is one of the moons of Mars
C.
on the Moon, because it is one of the largest craters
D.
in the asteroid belt


10.
The major volcanoes on Mars have formed
A.
in regions of ridges where the crust is being compressed and buckled without being subducted.
B.
directly above stationary hot-spots in the mantle.
C.
on long, interconnecting ridges and rifts, where magma rising from the mantle is pushing the crust apart.
D.
in mountain belts, where the crust is being subducted back into the mantle.


11.
The numerous small black spots on Jupiter's satellite Io appear to be
A.
impact craters.
B.
rocky outcrops.
C.
volcanic vents.
D.
sulfur deposits.


12.
Jupiter appears as a flattened, oblate spheroid in the sky because
A.
it is spinning rapidly, and is composed mostly of fluid matter.
B.
it was formed in this way at the time of planetary formation, and has solidified to this shape.
C.
tidal distortion from its moons and from the Sun have distorted its shape.
D.
it is moving rapidly around its orbit, flattening its shape.


13.
Although there is no official dividing line, a chunk of rock orbiting the Sun is generally considered an asteroid rather than a meteroid if it
A.
is larger than one centimeter across.
B.
is larger than 50 meters across.
C.
is larger than 2 kilometers across.
D.
has a mass larger than one percent the mass of Earth.


14.
Some of Saturn's moderate-sized satellites (smaller than Titan) have peculiar surfaces in which their leading hemispheres (pointing ahead in the satellite's orbit) are distinctly different from their trailing hemispheres. Which of the following does not show this distinct patterning?
A.
Iapetus
B.
Rhea
C.
Enceladus
D.
Dione


15.
Uranus and Neptune are similar in size and have similar atmospheres, but Neptune is significantly farther away from the Sun than is Uranus, by a ratio of about 30/19. What conclusion can be reached, therefore, from the fact that Neptune's temperature is about the same as Uranus's?
A.
Neptune's atmosphere must contain a more effective greenhouse gas to maintain more solar energy.
B.
Neptune must have a significant source of internal energy or heat.
C.
The solar wind is able to penetrate to Neptune's cloud-tops and deposit energy there, while Uranus's magnetic field deflects the solar wind.
D.
Neptune is being distorted, therefore heating more than Uranus by tidal effects from Jupiter and Saturn.


16.
Callisto, the outer Galilean moon of Jupiter, has a surface consisting of
A.
an icy crust showing two interlocking types of terrain, one ancient and heavily cratered, the other younger with systems of parallel grooves.
B.
an ancient, icy crust covered with numerous craters and no surface cracks or groove belts that would indicate internal activity.
C.
rock, heavily cratered like the highlands of our Moon.
D.
a relatively young, icy crust covered with a network of streaks and cracks, and only a few impact craters.


17.
There are several reasons the surface of Mars is more easily seen from Earth than any other planet's surface. Which of the following is NOT one of those reasons?
A.
relative proximity to Earth
B.
high mountain ranges casting strong shadows and providing high-contrast images
C.
visible high in the sky at midnight when at opposition
D.
a thin, almost cloudless atmosphere


18.
Neptune was discovered
A.
totally by accident.
B.
because of deviations observed in the orbit of Uranus.
C.
when it collided with a bright comet.
D.
by the Hubble Space Telescope (HST).


19.
In composition and density
A.
Io and Europa are more like Mars, whereas Ganymede and Callisto are more like Jupiter.
B.
Io and Europa are more like Jupiter, whereas Ganymede and Callisto are more like Mars.
C.
Io and Callisto are more like Mars, whereas Europa and Ganymede are more like Jupiter.
D.
Io and Callisto are more like Jupiter, whereas Europa and Ganymede are more like Mars.


20.
The physical structure of Saturn's rings is
A.
a thin, solid ring of rock and ice that is partly transparent.
B.
hot, ionized gas in a current sheet within the planet's magnetosphere.
C.
a thin but extensive gas cloud over the equator.
D.
a sequence of many hundreds of separate rings made of ice and rock particles.


21.
The most likely origin of the “dirty snowballs” that become long-period comets when deflected into orbits bringing them closer to the Sun, is
A.
the Oort cloud surrounding the Solar System.
B.
the surfaces of the moons of Jupiter and Saturn.
C.
the gas clouds in the Milky Way.
D.
the asteroid belt.


22.
How do the biggest asteroids compare in size with the Moon?
A.
They are very much smaller (less than 1/10).
B.
They are between 1/10 and 1/2 as large.
C.
They are about the same size.
D.
They are very much larger (greater than 5×).


23.
Often an asteroid viewed from Earth will appear to change its brightness periodically. We believe this happens because
A.
the albedo is significantly different on one side compared to the other.
B.
like Iapetus, a satellite of Saturn, the leading side is very dark and the trailing side is very bright.
C.
the asteroid is elongated, so that it may present a larger or a smaller cross section to us as it rotates.
D.
the asteroid is simply passing through the shadow of another asteroid.


24.
One of the striking features of the overall surface of Mars is
A.
the two very distinct hemispheres, one of them lower and smoother than its counterpart and almost free of craters.
B.
the presence of active volcanoes and lava flows over the whole surface, including near to the poles, where these flows melt the icecaps regularly.
C.
the remarkable similarity of surface features across the whole of the planet, including uniform distribution of craters and ancient river valleys.
D.
the uniform distribution of water-ice frost over the whole surface, hidden in the shade of rocks, both winter and summer.


25.
A typical comet loses what fraction of its mass each time it passes close to the Sun (i.e., at each perihelion passage)?
A.
less than 0.001%
B.
10%
C.
0.1%
D.
0.5% to 1%


26.
In what important way does the Jupiter-moon system resemble a miniature Solar System, perhaps providing a hint to the initial formation of both systems?
A.
The reflectivity of their surfaces decreases, the farther away they are from the central object, because the nearer objects have thicker clouds around them.
B.
Average density of objects decreases as distance increases from the central object, because the heat from this object would have melted and evaporated the volatile low-density ices from the closer objects.
C.
Average density of objects increases the farther away they are from the central object, because this central object can attract high-density material over a greater range of distances than for low-density material.
D.
The masses of objects increase as distance increases from the central object, because the probability of accretion of small objects into larger objects increases with distance.


27.
The smoothest body in the Solar System is
A.
Mercury.
B.
Europa.
C.
Ganymede.
D.
Enceladus.


28.
The smooth, dark maria on the Moon are
A.
areas that were still molten at the time of the early, heavy bombardment.
B.
immense impact basins that are smooth because they were covered by lava flows after a period of heavy bombardment early in the Moon's history.
C.
immense impact basins that are smooth because earlier craters were wiped out by shock waves from the impacts.
D.
regions that are as old as the cratered highlands but escaped a period of heavy bombardment by being on the “wrong” side of the Moon.


29.
The surfaces of Ganymede and Callisto appear to consist of
A.
sulfur.
B.
ices of methane, ammonia, and water.
C.
rocks and lava.
D.
water ice.


30.
On Jupiter and Saturn the wind currents move generally
A.
parallel to the equator.
B.
from north to south.
C.
from south to north.
D.
in totally random directions.


31.
How old are the lunar highlands?
A.
3.1 to 3.8 billion years old
B.
1.8 to 2.6 billion years old
C.
less than 1 billion years old
D.
4.0 to 4.3 billion years old


32.
What does Neptune look like from space?
A.
blue-green with white, high-altitude clouds and dark storms
B.
perpetually covered with yellowish, sulfur-rich clouds
C.
blue-green and featureless
D.
reddish belts and light zones parallel to the equator


33.
The astronomical event that is now thought to have occurred some 65 million years ago to produce a layer of iridium in the geological record in rocks and to have resulted in the deaths of a great fraction of all living species was
A.
a very large volcanic eruption on Earth.
B.
the impact of an asteroid on Earth.
C.
a supernova that exploded relatively near the Solar System.
D.
an extraordinary solar eruption or flare.


34.
What is the Great Red Spot on Jupiter?
A.
a large, long-lived, counterclockwise rotating storm maintained by high-speed wind and circulation in Jupiter's atmosphere
B.
the point where charged particles from the satellite Io collide with Jupiter's cloud tops
C.
a region over the south pole of Jupiter where ammonia compounds have condensed in the colder atmosphere
D.
clouds above the summit of a large volcanic mountain


35.
The ionized gas tail of a comet is always aligned with
A.
the celestial equator.
B.
the comet's direction of motion.
C.
the line between the comet and the nearest planet as it moves in its orbit.
D.
the comet-Sun line.


36.
The nucleus of Comet Halley, photographed close-up by the Giotto spacecraft, is
A.
oblong, with a bright ice surface.
B.
roughly spherical, moderately cratered, and covered with dark dust.
C.
roughly spherical, icy, and covered with many cracks and grooves.
D.
potato-shaped and darker than coal.


37.
Hot-spot volcanism is a process that
A.
produces gigantic volcanoes on Venus and Mars but produces chains of smaller volcanoes on Earth (e.g., the Hawaiian Islands).
B.
produces dome-shaped rises on Venus and Mars and mid-ocean ridges on Earth (e.g., the Mid-Atlantic Ridge).
C.
does not operate on Venus or Mars but produces subduction zones on Earth (e.g., along the west coast of North and South America).
D.
produces large rift valleys on Mars, Venus, and Earth (e.g., the Great Rift Valley of Africa).


38.
Some astronomers suspect that Saturn's satellite Enceladus could be heated enough by tidal flexing to produce active geysers of water on its surface, in a mechanism similar to that operating on Jupiter's satellite Io. Which one of the following statements is a correct observational fact supporting this conjecture?
A.
A strong electric current flows from Enceladus to Saturn along Saturn's magnetic lines of force.
B.
Enceladus is a “shepherd satellite” for the braided F ring, which could be made up of ice particles from the geysers.
C.
Active volcanoes were photographed on Enceladus by the Voyager spacecraft.
D.
Enceladus orbits inside the faint E ring, which may be made up of ice particles from the geysers.


39.
Stony meteorites
A.
are composed of rocks similar to terrestrial rocks.
B.
contain large quantities of carbon and H2O, and even hydrocarbons and amino acids.
C.
have solid iron cores and rocky silicate shells.
D.
are made of solid iron and nickel.


40.
Rings of dust and icy particles are found around which planets?
A.
all planets that have moons associated with them
B.
all four of the Jovian planets
C.
all four of the terrestrial planets
D.
only Saturn


41.
Evidence of volcanism (lava outflow, etc.), either active or ancient, is not found on
A.
Venus.
B.
Mars.
C.
Earth.
D.
Jupiter.


42.
The size distribution of particles in the rings of the Jovian planets is
A.
from pebble-sized fragments to objects a few meters in diameter with significant amounts of fine dust particles in some rings.
B.
a mixture of gas (mostly hydrogen) and dust grains, none larger than about 1 mm across.
C.
individual bodies varying in size from 10 m to 1 km across, with no smaller components.
D.
only dust and smoke-like particles.


43.
Which is the least dense planet in the solar system?
A.
Uranus
B.
Mercury
C.
Saturn
D.
Jupiter


44.
A meteoroid is the name for a solid particle that
A.
has burned up in Earth's atmosphere.
B.
originated on the Moon and has landed on Earth.
C.
has impacted on Earth's surface.
D.
is drifting around in space.


45.
What are the fractional proportions of the components that make up the mass of Jupiter?
A.
almost pure hydrogen, with at most about 1% rock in the core
B.
50% hydrogen, 49% helium, 1% rocky core
C.
71% hydrogen and helium, 25% rocky core, 4% everything else
D.
95% hydrogen and helium, 5% everything else


46.
Libration is
A.
apparent wobbling of the Moon due to the shape and orientation of its orbit and rotation axis.
B.
a custom of toasting astronauts with champagne when they touch down on the Moon.
C.
exact synchronicity between orbital motion of the Moon and its rotation about its own axis.
D.
gradual movement of the terminator across the visible face of the Moon.


47.
What would be a typical weather forecast on Titan, Saturn's largest moon?
A.
dust storms and high winds in a thin CO2 atmosphere
B.
turbulent winds in an ammonia, methane, and water vapor atmosphere, with dense clouds of ammonia compounds and water ice
C.
hydrocarbon fog and ethane rain in a nitrogen atmosphere
D.
occasional sulfur clouds and sulfur dioxide fog from volcanic eruptions


48.
If Uranus and Neptune had the same abundance of the elements as Jupiter and Saturn
A.
they would have the same densities as Jupiter and Saturn even though they have smaller masses.
B.
they would have smaller densities than Jupiter and Saturn because density is proportional to mass, implying that smaller masses always have smaller densities.
C.
they would have larger densities than Jupiter and Saturn because density is inversely proportional to volume, implying that smaller volumes always have larger densities.
D.
They would have smaller densities than Jupiter and Saturn because their smaller masses would produce less gravity, and the materials would be compressed less.


49.
When Venus is at its brightest as seen from Earth (near greatest elongation), it is
A.
the brightest celestial object in the sky other than the Sun and Moon.
B.
brighter than the full Moon but not as bright as the Sun.
C.
just bright enough to be seen with the unaided eye if one knows exactly where to look for it.
D.
too faint to see without binoculars or a telescope.


50.
The brown ovals which are seen in Jupiters atmosphere appear bright in an image taken in infrared radiation. Why is this?
A.
The ovals are moving toward us, and the Doppler blueshift makes them appear brighter.
B.
The ovals are moving away from us , and the Doppler redshift makes them appear brighter.
C.
The ovals are high up in the Jovian atmosphere.
D.
The ovals are deep within the Jovian atmosphere.


51.
The ages of Moon rocks have been found through radioactive dating. One major difficulty with this technique is that
A.
the original abundances of the elements are not precisely known.
B.
relatively large samples (approximately 10 cm in diameter) are needed for testing.
C.
the half-lives of the elements are not precisely known.
D.
the age of the Moon is greater than the half-life of any of the radioactive elements.


52.
Most comet nuclei are believed to be
A.
chunks of rock or iron chipped from asteroids by impacts.
B.
large carbon chondrite meteoroids that have been set on fire by the Sun and are trailing long smoke trails.
C.
chunks of water and methane ice ejected from the surface of the icy satellites of the outer planets by asteroid impacts.
D.
chunks of dirty ice left over from the formation of the Solar System.


53.
The major difference between the orbital paths of most asteroids and those of comets is that
A.
comet orbits are mostly circular and in the ecliptic plane, whereas asteroids have elliptical orbits inclined at random to the ecliptic plane.
B.
comets never approach closer to the Sun than approximately Jupiter's orbit, whereas some asteroids approach very close to the Sun.
C.
asteroids orbit the Sun continuously, whereas all comets approach the Sun's vicinity only once before leaving the Solar System.
D.
comet orbits are highly elliptical and at random inclinations to the ecliptic plane, whereas asteroids have circular orbits in the ecliptic plane.


54.
The rings of Uranus are
A.
wide, dense, ice-covered, and hence very bright (70% reflectivity).
B.
narrow and very dark (1% reflectivity).
C.
intrinsically very bright (70% reflectivity) but hard to detect because they are very narrow.
D.
broad, diffuse (almost transparent) bands, made up of fine dust particles.


55.
The heating of the interior of the large Galilean moon Io of Jupiter, in order to produce volcanic activity, is probably caused by
A.
its original heat of formation.
B.
radioactive elements in its surface.
C.
nuclear fission within its interior.
D.
tidal distortion by Jupiter and its other moons.


56.
We have discovered that the temperature in Jupiter's atmosphere increases as one moves inward toward the planet, and that the planet gives out more energy than it receives from the Sun. What is the cause of this?
A.
the greenhouse effect
B.
the Kelvin-Helmholtz Contraction
C.
nuclear reactions in Jupiter's interior
D.
radioactivity in minerals in Jupiter's rocky core


57.
Which object was discovered as a result of the detailed prediction of its position using Newton's gravitational theory to explain deviations in the motions of known planets?
A.
Pluto
B.
Neptune
C.
Mercury
D.
Saturn


58.
The smooth, dark maria take up what fraction of the entire surface of the Moon?
A.
less than 1/5
B.
between 1/2 and 3/4
C.
more than 4/5
D.
between 1/3 and 1/2


59.
The Moon has
A.
an atmosphere of CO2, but no evidence of water.
B.
a lot of evidence for an atmosphere and the presence of liquid water (e.g., wind erosion and winding river valleys).
C.
no measurable atmosphere or liquid water.
D.
no measurable atmosphere, but plenty of groundwater.


60.
What is the current state of plate tectonics on the Moon?
A.
just in the process of beginning; the rilles (or sinuous valleys) are the first signs of continental rifting
B.
very active, causing mountain uplift around the edges of several lunar maria
C.
dying out; only the lunar maria show signs of tectonic movement today
D.
absent; the Moon is a geologically dead world


61.
To what does the phrase “synchronous rotation” for an astronomical object (e.g., planet or moon) refer?
A.
It has a rotation rate that is precisely maintained (e.g., 23 h 56 m 4.096 s for Earth).
B.
For an object in an elliptical orbit, the rotation rate increases and decreases to match the changes in its orbital speed.
C.
It completes precisely one rotation around its own axis for every orbit (1-1 spin-orbit coupling).
D.
It has any rotation period that is in simple proportion to its orbital period (1-1 spin-orbit coupling, 3-2 spin-orbit coupling, etc.).


62.
What is believed to be the cause of the long, meandering scarps (cliffs) observed on Mercury?
A.
shrinkage of the planet as Mercury cooled
B.
large impacts near the end of the early period of heavy bombardment
C.
volcanic eruptions along crustal faults over hot spots in the mantle
D.
crustal movement due to convection in the mantle, similar to continental drift on Earth but to a much smaller extent


63.
The Great Red Spot is
A.
a rapidly rotating large region at the north pole of Saturn.
B.
a hot-spot on Venus detected by Russian landers and the U.S. Magellan orbiter.
C.
a large, stable, circulating storm system in the atmosphere of Jupiter.
D.
a large red crater on Mars.


64.
What is the Kuiper belt?
A.
a band of dust in the plane of the ecliptic, extending from near the orbit of Mars to beyond the orbit of Pluto
B.
the broadest band of asteroids in the asteroid belt, separated from other bands by Kirkwood Gaps
C.
a relatively flat distribution of objects in the plane of the ecliptic, extending from around the orbit of Pluto out to about 50 AU from the Sun
D.
an approximate spherical distribution of comets centered on the Sun, and extending out to about 50,000 AU


65.
Venus has a higher surface temperature than Mercury. Which of the following is an explanation for this?
A.
Venus is closer to the Sun than Mercury is.
B.
Venus has a dense atmosphere of carbon dioxide.
C.
Venus is still contracting gravitationally and thus gives out more radiation than it receives.
D.
Venus has a higher albedo (reflectance) than Mercury.


66.
A friend who says that he is an astronomer claims that he was outside at midnight a few weeks ago looking at Mercury. What should be your response?
A.
“Oh, you must have been in Australia or South America since Mercury can be seen at midnight only from the southern hemisphere.”
B.
“You must be mistaken, because Mercury NEVER appears in our midnight sky.”
C.
“Really! Have you just purchased a new telescope? Mercury can be seen at midnight only through a telescope.”
D.
“Congratulations, you have been fortunate enough to see Mercury on a very rare occasion.”


67.
For someone standing on the surface of Jupiter, tomorrow's weather forecast is
A.
sunny, possible thin, high clouds.
B.
sunny and clear, because Jupiter has no atmosphere in which clouds can form.
C.
overcast, possible rain with snow at higher elevations.
D.
The question is meaningless, because there is no solid surface on which to stand.


68.
An asteroid is
A.
another name for the nucleus of a comet, a volatile object that moves around the Sun in a long, elliptical orbit.
B.
an object smaller than a planet, moving around the Sun in an orbit close to the plane of the ecliptic.
C.
a meteorite before it enters the atmosphere and plunges to Earth.
D.
a small, easily recognizable group of stars within a constellation.


69.
Asteroids that orbit the Sun at the same distance as Jupiter are known as the
A.
Adenoids.
B.
Apollo asteroids.
C.
Trojan asteroids.
D.
Jupitoids.


70.
What is significant about the rotational and revolutional motions of the Galilean moons of Jupiter?
A.
synchronous rotation with one face always pointed toward the planet
B.
nonsynchronous rotation with independent periods of rotation and revolution, and spin axes perpendicular to their orbit
C.
nonsynchronous rotation with axes of rotation in any direction with respect to their orbital plane
D.
synchronous rotation with one face always pointed toward the Sun


71.
The Great Dark Spot on Neptune, photographed by Voyager 2 during its flyby of the planet, was
A.
a cyclonic system with clockwise winds, opposite to those in Jupiter's Great Red Spot.
B.
a cyclonic system with counterclockwise winds, the same direction as those in Jupiter's Great Red Spot.
C.
a volcanic caldera.
D.
a region of upwelling gas in Neptune's atmosphere, above a hot-spot on its surface.


72.
Jupiter's satellite Europa is believed to be made up of
A.
ice, with possibly a small, rocky core.
B.
rock only.
C.
ice and rock mixed throughout in roughly equal proportions.
D.
a metallic inner core and a rocky outer core covered by an “ocean” of ice.


73.
Dust grains released by the melting of ice in a comet nucleus
A.
drift away from the Sun along magnetic field lines, outlining the structure of this field.
B.
become a uniform, curved tail, moving away from the comet under radiation pressure from sunlight.
C.
become a cloud around the nucleus, the coma, scattering sunlight very efficiently at blue wavelengths.
D.
become a straight, highly structured, and very variable tail, blown away from the comet by the solar wind.


74.
A regolith is
A.
a layer of pulverized rock on the surface of a planet or other object.
B.
an extremely large, isolated rock on the surface of a planet or other object.
C.
a heavily cratered region on a planet or other object.
D.
a lithospheric plate, moved slowly by geologic processes.


75.
The Great Dark Spot (which is not the same as the Great Red Spot) was found on which planet or moon?
A.
Mars
B.
Jupiter
C.
Miranda, a moon of Uranus
D.
Neptune


76.
Which satellite of Jupiter is volcanically active?
A.
Europa
B.
Ganymede
C.
Callisto
D.
Io


77.
How does Saturn's size (e.g., diameter) compare to that of Jupiter?
A.
slightly larger—because Saturn is rotating much faster then Jupiter
B.
significantly larger—because Saturn contains a greater proportion of hydrogen than Jupiter
C.
about the same—because Saturn is less massive and less compressed
D.
significantly smaller—because Saturn has only about one tenth the mass of Jupiter


78.
Most asteroids
A.
are dark and spherical in shape, with many craters on their surfaces.
B.
are spherical and ice-coated and hence light-colored and shiny.
C.
are irregularly shaped and covered with very light-colored dust that reflects sunlight well.
D.
are dark, irregular in shape, and heavily cratered.


79.
Suppose that two regions on the Moon have ages, respectively, of 3.7 and 4.3 billion years. Based on these ages, we expect to find that
A.
the older region has fewer craters than the younger region because the cratering rate was lower at earlier times.
B.
both regions have roughly the same amount of cratering because they have approximately the same age.
C.
the older region has 16% more craters than the younger region because its age is 16% greater than that of the younger region.
D.
the older region has far more craters than the younger region because of changes in the cratering rate over that time.


80.
Most surface rocks on Earth are younger than a few million years old, whereas ages of lunar rocks have been measured in billions of years. Why is this?
A.
The complete surface of Earth has been covered periodically by younger material from intense volcanic eruptions in the last few million years. No such activity has occurred on the Moon.
B.
Earth's surface undergoes continuous recycling through the underlying mantle because of plate tectonic activity, and this does not occur on the Moon.
C.
The ages of Earth and the Moon are fundamentally different, the Moon being an old object captured from deep space by a younger Earth.
D.
Most of the early surface rocks of Earth have been washed into the sea by weathering and rainwater, and this does not happen on the Moon.


81.
The near and far sides of the Moon are particularly different in that
A.
the far side is always in darkness.
B.
the average height of the overall terrain is much lower on the far side.
C.
the far side has no maria.
D.
the number of craters differs markedly, with fewer on the far side.


82.
Because its interior is so hot, Jupiter radiates about twice as much heat as it receives from the Sun. How does this fraction compare with the excess energy radiated by Earth as a fraction of the energy Earth receives from the Sun?
A.
It is about the same.
B.
The fraction is about 10 times larger for Jupiter.
C.
The fraction is about 1000 times larger for Jupiter.
D.
The fraction is about 104 times larger for Jupiter.


83.
Which of the following is the best explanation for the origin of the Moon?
A.
The Moon was created in its orbit around Earth by the same process which produced earth, namely the collision of planetesimals which had formed by condensation and accretion of gas and dust.
B.
The Moon was created by the process described above, but at some other location in the solar system.
C.
While Earth was semi-molten early in its formation, a chunk of material was flung out of it. It went into orbit and evolved to become the Moon.
D.
The same as answer C) except that the ejection was caused by a large impact of some object into Earth.


84.
What feature of the Hawaiian Islands is similar to many geological features on Mars and Venus?
A.
They, like the major mountains on Venus and Mars, were formed by upthrust from collisions of two tectonic plates.
B.
They were produced by impacts of massive asteroid-like bodies on the ancient Earth and are now being eroded by the ocean.
C.
They were produced by slow build-up of coral reefs in ancient oceans.
D.
They, like mountains on Venus and Mars, were produced by hot-spot volcanism and upflow of heat from below.


85.
The composition of Saturn's rings is
A.
particles of methane and ammonia ice.
B.
small grains of rock.
C.
sodium and sulfur ions.
D.
water ice or ice-coated rock.


86.
Saturn's moon Titan is different from all other moons of planets because
A.
lakes of water with floating icebergs are seen upon its surface.
B.
it possesses a thick atmosphere.
C.
its orbit carries it directly over both poles of the planet.
D.
continuously erupting volcanoes are observed upon it.


87.
Which planet is characterized by a blue-green appearance, with dark storms and white, high-altitude methane clouds?
A.
Saturn
B.
Jupiter
C.
Neptune
D.
Uranus


88.
Earth has several lithospheric plates that gradually move in a process called plate tectonics. How many such plates are there on the Moon?
A.
one; the entire lithosphere is a single plate
B.
five; one for each of the major lunar seas (maria)
C.
six; one for the highlands (terrae) and one for each of the major lunar seas (maria)
D.
two; the region of the near side occupied by the seas (maria) forms one plate, and the rest of the Moon (the bulk of the highlands, or terrae) forms the other


89.
The diameter of the Moon is
A.
less than 1/100 of the diameter of Earth.
B.
about 1/10 of the diameter of Earth.
C.
about 1/4 of the diameter of Earth.
D.
just over 1/2 the diameter of Earth.


90.
The impact craters on Earth are younger than a few million years old, whereas ages of lunar craters extend back billions of years. Why is this?
A.
Earth escaped the heavy bombardment that pelted the Moon early in its history.
B.
Earth's surface has been covered by lava flows several times in its history, whereas such activity ceased on the Moon several million years ago.
C.
Weathering by rain and melting snow gradually erases craters on Earth, and this does not happen on the Moon.
D.
Plate tectonics has erased older craters on Earth, whereas this process has not occurred on the Moon.


91.
Oblateness is a measure of the
A.
nonspherical shape of a planet, with the polar diameter being shorter than the equatorial diameter.
B.
nonspherical shape of a planet, with the polar diameter being longer than the equatorial diameter.
C.
inclination of the orbit of a planet or a moon to the ecliptic plane.
D.
noncircular shape of a planet's orbit.


92.
How would "Interplanetary Travel" advertise a holiday on Titan, one of the satellites of Saturn?
A.
The largest number of volcanoes for your travel dollar anywhere in the Solar System!
B.
Methane rain!
C.
Glaciers galore for your hiking pleasure under star-studded skies!
D.
Hot and dry—never rains—beautiful sulfurous skies!


93.
The impact that took place at about the time of the extinction of the dinosaurs (and may in fact have caused their extinction) is believed to have created
A.
the Barringer Crater in Arizona.
B.
the Chicxulub Crater in the Yucatan Peninsula, Mexico.
C.
Hudson Bay in northern Canada.
D.
the Manicouagan Crater in Quebec.


94.
Consider a large lunar crater, say 100 km across. What probably caused its formation?
A.
a projectile 100 km across
B.
a projectile larger than 100 km across (since much of it would vaporize on impact)
C.
the shock wave generated by a projectile considerably less than 100 km across
D.
a lunar volcano


95.
What has proven to be the best method for measuring the mass of a Galilean moon of Jupiter?
A.
observing its orbital motion around Jupiter and applying Kepler's Laws
B.
measuring the density of material using a lunar lander vehicle and multiplying this density value by the moon's volume
C.
measuring the mutual gravitational disturbances of the orbits of neighboring moons by the moon
D.
observing the slight changes in the motion of a spacecraft caused by gravitational force, as the spacecraft passed near the moon


96.
Which of the following is believed to be the correct explanation for the origin of the Moon?
A.
The Moon was formed elsewhere in the solar system (which is why its composition differs from that of Earth) and was later captured by Earth's gravity.
B.
Shortly after its formation, Earth was spinning so fast in its molten state that a large piece of material was thrown off, and this coalesced to form the Moon—leaving the Pacific Ocean Basin in the place where it was thrown off.
C.
Earth and the Moon were formed separately at the same time, while in orbit around their common center of mass, by the accretion of planetesimals.
D.
Earth was struck by a large planetesima, which caused material to be ejected. This material coalesced to form the Moon.


97.
Because of mutual gravitational forces between the moons and the planet, the orbital periods of the three inner Galilean moons of Jupiter are in the ratio
A.
1:2:3.
B.
1:10:100.
C.
1:1:1—equal orbital periods.
D.
1:2:4.


98.
The deepest central cores of the interiors of Jupiter and Saturn are thought to be composed of
A.
methane, ammonia, and water vapor.
B.
liquid metallic hydrogen.
C.
magnetized iron.
D.
rock.


99.
The moons of Mars are
A.
spherical and quite large, compared to the planet; about 1000 km in diameter, similar to the largest asteroid.
B.
irregular but quite large, compared to the planet, between 500 and 1500 km across.
C.
irregular in shape and very small, only several tens of kilometers across.
D.
almost spherical but very small, between 10 and 30 km in diameter.


100.
The dominant component of the soil on Mars is probably
A.
sedimentary rocks laid down by massive floods early in Mars's history.
B.
basaltic lava pulverized by meteoritic bombardment.
C.
iron oxides.
D.
volcanic ash from eruptions in recent geological times.


101.
The rings of Saturn orbit the planet
A.
as a solid body.
B.
as five separate solid rings.
C.
as individual particles, all with periods shorter than the large moons of Saturn.
D.
as individual particles, all with periods longer than the large moons of Saturn..


102.
What physical mechanisms most probably caused the very long cracks and streaks that crisscross the surface of Europa, a moon of Jupiter?
A.
They are the tops of gigantic greenhouses built by inhabitants of Europa to protect their cucumber crops.
B.
They are frozen rivers which, in warmer times, flowed across the moon's surface.
C.
Volcanic eruptions caused lava flows which then froze in place.
D.
tidal flexing and cracking of the surface, with subsurface fluids gushing upward and freezing


103.
Which one of the following four theories about the origin of the Moon is now believed to be correct?
A.
An object about the size of Mars crashed into Earth and debris from the collision formed the Moon.
B.
Earth and the Moon formed together, already orbiting each other.
C.
The Moon formed separately in a different part of the solar nebula and was later captured by Earth.
D.
Earth was spinning so rapidly while still molten that a piece “spun off” to form the Moon.


104.
A comet's gas and ion tail
A.
always lies in the ecliptic plane, because a comet is a part of the Solar System.
B.
lies between the comet and the Sun, because of gravitational attraction.
C.
always trails along the orbital path, because of the comet's motion.
D.
is always blown away from the comet in the anti-Sun direction by the solar wind.


105.
When Mercury is at greatest elongation it is sometimes at a more favorable position for viewing and sometimes at a less favorable position for viewing. What can change from one occurrence of greatest elongation to the next to cause this difference?
A.
the eccentricity of Mercury's orbit
B.
the inclination of Mercury's orbit relative to the ecliptic
C.
the position of Mercury in its orbit
D.
the direction in space of the semimajor axis of Mercury's orbit


106.
What chemical substances are believed to be the source of the many colors seen on the surface of Io, the inner large satellite of Jupiter?
A.
iron and iron oxides or rust
B.
sulfur and sulfur compounds
C.
organic (carbon) compounds discolored by solar ultraviolet light
D.
impurities in a water-ice crust


107.
What significant evidence exists for the idea that large quantities of water once flowed on the planet Mars?
A.
clouds and frost forming above and around the Viking spacecraft, released by the heat of the descent rockets
B.
frozen but dust-covered lakes inside ancient craters
C.
a network of relatively straight canals linking polar and equatorial regions
D.
deep, winding canyons and flood plains


108.
What is believed to be the basic structure of the interior of Uranus?
A.
rocky core, thick layer of water, thin gaseous atmosphere
B.
iron core, thick layer of rock, thin gaseous atmosphere
C.
rocky core, thick layer of water, thick layer of liquid hydrogen, thin gaseous atmosphere
D.
rocky core, thick layer of liquid hydrogen, thin gaseous atmosphere


109.
Detailed observations of Jupiter's rotation suggest that
A.
it is not a rigid object, because equatorial regions rotate faster than polar regions.
B.
it rotates in two separate parts, equatorial regions rotating in a direction opposite to polar regions.
C.
it is slowing down noticeably at the present time.
D.
it rotates like a solid body, with equatorial and polar regions having the same rotational period.


110.
The source of intense heating in the interior of Jupiter's moon Io, causing continuous and intense volcanic activity, is
A.
tidal flexing and distortion, caused by Jupiter and the other large moons.
B.
frictional heating as the solar wind impacts on the moon surface.
C.
solar UV and visible radiation.
D.
heat released by continuous shrinkage after creation, transforming potential gravitational energy to heat.


111.
In what way was the production of the Hawaiian Islands on Earth similar to the production of some of the major mountains on Mars and Venus?
A.
They were produced by hot-spot volcanism and upflow of heat from below.
B.
They were produced by impacts of massive asteroids during the ancient heavy bombardment period, and are now being eroded by wind and water.
C.
They were produced by slow buildup of coral reefs in ancient oceans.
D.
They were formed by upthrust from collisions of two tectonic plates.


112.
Which of the giant Jovian planets has an internal energy source which is so weak that it is masked by the energy received from the Sun so that, from evidence of excess infrared emission, it appears not to be generating energy internally?
A.
Jupiter
B.
Saturn
C.
Uranus
D.
Neptune


113.
Statistically, an asteroid one kilometer in diameter might be expected to strike Earth
A.
during an interval of 80 years – roughly a human lifetime.
B.
once every 10,000 years.
C.
once every 300,000 years.
D.
never.


114.
The particles in Saturn's rings are composed of
A.
a mixture of iron and nickel.
B.
water ice or rock coated with water ice.
C.
ammonia and methane ice, possibly with rocky centers.
D.
rocks with the reflectivity of dark asphalt.


115.
On Mars, the air pressure varies much more from one season to another than it does on Earth. Why is this?
A.
Seasonal dust storms on Mars blanket the entire planet, increasing the weight of the atmosphere.
B.
Because the atmosphere of Mars is so thin, water vapor condensing on the polar ice caps in winter removes a much larger fraction of the atmosphere than on Earth.
C.
Because of the low density of the atmosphere, solar heating has a much larger effect on Mars than on Earth.
D.
On Mars, much of the CO2, the major constituent of the atmosphere, condenses out to the surface as snow. This gas is only a minor constituent in Earth's atmosphere.


116.
Why does the innermost Galilean moon of Jupiter, Io, not show a cratered surface, as expected from the appearance of equivalent-sized objects like our Moon, Mercury, and Mars?
A.
The large gravitational force generated by Jupiter has diverted most objects away from Io.
B.
The surface is completely covered by an ocean of water, partly frozen into ice, which will obviously not show craters.
C.
Volcanic action recoats the surface regularly and continuously.
D.
Dust storms triggered by heating from Jupiter have quickly filled in any craters.


117.
The “ snow” that occasionally falls upon Mars and covers the bottoms of craters is most probably made of
A.
very fine white dust, disturbed occasionally by fierce wind storms.
B.
carbon dioxide ice.
C.
water ice.
D.
frozen sulfuric acid droplets.


118.
Which of the large moons of the Jovian planets appears to have a significant and permanent magnetic field?
A.
Europa
B.
Ganymede
C.
Callisto
D.
Titan


119.
The pressure of the atmosphere of Mars—primarily carbon dioxide (CO2)—compared to the atmospheric pressure at Earth's surface, is
A.
extremely small (less than 1 millionth).
B.
about 90 times greater.
C.
less than 1/100.
D.
about the same.


120.
The Trojan asteroids orbit the Sun in circular orbits at the same distance as
A.
the main asteroid belt.
B.
Jupiter.
C.
Mars.
D.
Earth.


121.
What effect causes the seasonal variation in color and shading of parts of the Martian surface?
A.
changes in dust covering in response to wind storms
B.
changes in the fluorescent glow caused by the varying intensity of solar UV radiation
C.
growth and decay of vegetation
D.
moisture falling as light rain, dampening the surface


122.
How did optical illusion mislead early visual observers of Mars?
A.
Apparent movement of surface features because of fluctuations in images when viewed through Earth's atmosphere, were interpreted as evidence for moving life-forms or Martians.
B.
Volcano and rock structures were seen as eye-shaped and face-like and were interpreted as having been made by intelligent beings to indicate their presence.
C.
Moving areas of obscured detail on the planet were interpreted as massive flash floods rather than dust storms.
D.
Chance alignments of faint, dark features looked like canals whereas darker areas, when viewed against the orange-red surface, were interpreted as vegetation.


123.
Detailed examination of the overall surface of the Moon and of the rocks brought back by Apollo astronauts reveals that
A.
unlike Earth's rocks, there is no evidence of water locked into crystal structures in lunar rocks, but there are significant quantities of ice in cold lunar polar regions.
B.
no water exists in either liquid form or ice now but, like terrestrial rocks, some water is contained within the crystal structure of lunar rocks.
C.
there have been short periods in recent history when water existed on the Moon, during which the rilles or river valleys were formed.
D.
water probably existed on the Moon earlier and formed lake beds or maria, but it has evaporated.


124.
The best time to observe Jupiter from Earth is when it is
A.
at conjunction—when it appears closest to the Sun and is at its brightest.
B.
at maximum eastern or western elongation and is farthest away from the Sun in our sky at sunrise or sunset.
C.
high above our southern horizon at sunrise or sunset.
D.
at opposition—hence closest to Earth.


125.
On Mars, which of the following features have not been detected?
A.
dust storms and dust devils
B.
advancing and receding polar ice caps
C.
thin, wispy clouds
D.
active volcanoes


126.
The dark, reddish bands across the surface of Jupiter are known as
A.
great circles.
B.
brown ovals.
C.
zones.
D.
belts.


127.
The planet Saturn appears to be
A.
a “sphere,” flattened along its polar diameter, significantly more so than for the planet Jupiter.
B.
a “sphere,” flattened along its polar diameter, considerably less than for Jupiter.
C.
a “sphere” in which the equatorial diameter is significantly less than the polar diameter because of the planet's rapid rotation.
D.
almost a perfect sphere, with equal polar and equatorial diameters.


128.
The four giant moons of Jupiter were discovered by
A.
the Pioneer spacecraft.
B.
Galileo.
C.
Ptolemy.
D.
Newton.


129.
How long is a “lunar day,” or the time between two successive sunrises or sunsets on the Moon?
A.
about 1 month
B.
infinitely long, because the Moon does not rotate about its axis with respect to the Sun
C.
about 1 year
D.
about 1 day


130.
When viewed in the infrared light emitted by the clouds, the brightest parts of Jupiter are
A.
in the belts, which correspond to deeper and hotter regions.
B.
directly along the equator, where sunlight is most direct and effective in heating the gas.
C.
in the zones, corresponding as expected to brighter regions in visible light.
D.
over the north and south magnetic poles, where magnetospheric interaction heats the atmosphere.


131.
The surface features and topology of Venus have been determined primarily by
A.
radar methods from Earth and from Venus-orbiting spacecraft detecting reflected radio waves from the surface.
B.
surface lander vehicles that have explored the surface.
C.
visible light and UV photography from the Hubble Space Telescope and Earth-bound telescopes.
D.
balloon-borne spacecraft launched into the Venus atmosphere by spacecraft.


132.
Why do the meteors that are seen in the sky in a particular meteor shower appear to come from one specific direction in the sky?
A.
Meteors appear only to come from a specific direction because of Earth's orbital motion.
B.
This specific direction is always along the ecliptic plane because meteor showers occur when Earth catches up with a bunch of particles moving in Earth's orbit.
C.
This is the direction of the orbit of the comet that disintegrated to produce the shower.
D.
This direction is that along which objects being attracted to the Sun by its gravity will pass.


133.
Jupiter's ring was discovered by
A.
direct, ground-based photography.
B.
momentary occultation of starlight as the planet and the rings moved in front of a star.
C.
visual observations by Galileo.
D.
spacecraft photography.


134.
The asteroid belt is believed by most astronomers to be composed of
A.
icy fragments similar to the nuclei of comets.
B.
genuine leather.
C.
rocky debris left over from the formation of the Solar System.
D.
the remnants of a gaseous planet disrupted by an impact.


135.
What kinds of large-scale changes have occurred on the Moon in the last billion years?
A.
None. The Moon is exactly as it was a billion years ago.
B.
tectonic activity
C.
volcanic activity and large scale lava flows
D.
Constant meteoroid impact has gently sculpted the landscape.


136.
A shooting star is
A.
a violently erupting star, ejecting matter rapidly away from it into interstellar space.
B.
a small particle of interplanetary dust, burning up and glowing as it enters Earth's atmosphere.
C.
the leading scorer on a basketball team.
D.
a near-neighbor star, moving rapidly across our field of view.


137.
The source of Jupiter's intense magnetic field is
A.
electric currents in ionized layers of Jupiter's atmosphere.
B.
remnant magnetism in Jupiter's rock and iron core.
C.
electric currents in Jupiter's liquid hydrogen mantle.
D.
electric currents in Jupiter's molten rocky core.


138.
A few meteorites on Earth are believed to have come from another planet. Which planet is this?
A.
Mars
B.
Jupiter
C.
Venus
D.
Mercury


139.
The reason for the slightly flattened or oblate shape of Jupiter is
A.
its rapid rotation rate.
B.
its cloud cover, more clouds forming over the equator on average.
C.
that it was formed that way in the beginning and has maintained this shape.
D.
the gravitational pull of the Sun and the other planets in the ecliptic.


140.
Earth's rotation is slowing down because of the tidal interaction between Earth and the Moon at a rate of 2 msec per century. If this rate remains constant at the present value, how long will it take for one day on Earth to become 2 seconds longer than it is now?
A.
1 million years
B.
100 million years
C.
1000 years
D.
100,000 years


141.
The combined matter in the asteroid belt would produce an object of what approximate size?
A.
about 1500 km in diameter—significantly smaller than the Moon
B.
about the size of Earth
C.
only a few kilometers in diameter—similar to an average mountain on Earth
D.
about the size of Mercury


142.
The carbon dioxide atmosphere of Mars was much denser in Mars's early history than it is now. What process is now believed to have begun this atmospheric thinning?
A.
The solar wind stripped the outer atmosphere from the planet.
B.
The light CO2 molecules escaped directly into space because of the weak gravity of Mars.
C.
The CO2 molecules were broken down by solar UV photons, creating the lighter molecules, CO and O2, which then escaped into space.
D.
The CO2 was washed out of the atmosphere by rain.


143.
The large-scale atmospheric circulation pattern on Jupiter is characterized predominantly by
A.
strong winds blowing parallel to the equator but in opposite directions at different latitudes.
B.
strong winds blowing eastward at all latitudes so that the entire atmosphere rotates faster than the planet.
C.
isolated cyclones (low-pressure areas) and anticyclones (high-pressure areas), as on Earth.
D.
strong winds blowing westward at all latitudes so that the entire atmosphere rotates more slowly.


144.
How would "Interplanetary Travel" advertise a holiday to Neptune's satellite Triton?
A.
The largest number of volcanoes for your travel dollar anywhere in the Solar System!
B.
Hot and dry—never rains—beautiful sulfurous skies!
C.
Skate on frozen nitrogen lakes all morning—bask beside nitrogen geysers in the afternoon!
D.
Exquisite ethane lakes—hydrocarbons beyond your wildest dreams!


145.
When Mercury is at its least value of greatest elongation it is 18° from Earth-Sun line. How long before sunrise (or after sunset) will Mercury be visible at this time?
A.
18 minutes
B.
about an hour
C.
two hours
D.
four hours


146.
The largest satellite (moon) in our planetary system is
A.
the Earth's Moon.
B.
Titan, a moon of Saturn.
C.
Phobos, one of the moons of Mars.
D.
Ganymede, a moon of Jupiter.


147.
A meteor shower results from
A.
material re-entering Earth's atmosphere after being ejected into space by violent volcanic eruptions on Earth.
B.
a small piece of rock or asteroid fragmenting as it passes through Earth's atmosphere.
C.
a meteor passing through a rain cloud on Earth.
D.
Earth passing through debris strewn along a comet's orbit.


148.
Which of the following governs the direction in which a comet's ion tail is aligned in space?
A.
its direction of motion, because the tail simply trails behind it in its orbit
B.
the gravitational attraction of the Sun for the tail material
C.
the gravitational attraction of Earth for the tail material
D.
the flow of solar wind past the comet's nucleus


149.
No heavy materials (iron, nickel, etc) have been found in the atmosphere of Jupiter. This is because
A.
they have evaporated away.
B.
there were no heavy materials in that part of the solar system where Jupiter was formed.
C.
they have sunk to the center.
D.
of impacts early in the history of the solar system which ejected these materials to form satellites.


150.
In its orbit around Earth, the Moon
A.
always keeps the sunlit side toward Earth.
B.
always keeps the same side toward the Sun.
C.
always keeps the same side toward Earth.
D.
rotates once every 24 hours to keep in step with Earth.


151.
The theory that seems to account most satisfactorily for the origin of the Moon at the present time is that
A.
the Moon formed from material spun off from Earth when Earth was molten and spinning rapidly, early in its history.
B.
a large object collided with Earth and ejected the material that formed the Moon.
C.
the Moon formed by accretion elsewhere in the solar system and was captured later by Earth.
D.
the Moon formed from material already in orbit around Earth.


152.
The rings of Saturn are seen by
A.
fluorescence, a glow produced by photochemistry when material is illuminated by solar UV light and/or high-speed cosmic particles.
B.
emitted light from the molecules of the material of the rings, such as methane, ammonia, and so on.
C.
reflected and scattered sunlight.
D.
reflected light from Saturn, since we can see them at night.


153.
What does the surface of Europa, a moon of Jupiter, look like?
A.
entirely ice, with fractures and ridges going in every direction and no features more than about 100 m high
B.
entirely ice, with light and dark areas containing many impact craters and parallel ridges up to about 1 km high
C.
rocky and densely cratered, except for a few large, dark, relatively uncratered plains
D.
We don't know; the surface is hidden below a dense layer of clouds.


154.
The Kirkwood Gaps are primarily caused by
A.
the gravitational tug of Jupiter nudging asteroids into new orbits.
B.
shepherd satellites controlling the orbits of ring particles.
C.
orbits of material being disturbed because Jupiter's gravitational field balances the Sun at this distance, and objects can escape from the Solar System.
D.
large asteroids sweeping parts of the asteroid belt clear of smaller asteroids.


155.
The inner two Galilean satellites of Jupiter differ from the outer two by having
A.
much higher average densities.
B.
almost the same average density, but much older, more heavily cratered surfaces.
C.
much lower average densities.
D.
almost the same average density, but much younger, less-cratered surfaces.


156.
On the basis of the surface and atmospheric conditions existing on Mars today, why could there be no permanent liquid water on its surface?
A.
The water would boil and evaporate rapidly under the low atmospheric pressure or freeze to ice at the low surface temperatures.
B.
It would have reacted chemically with the surface rocks.
C.
The UV radiation from the Sun would have dissociated the water molecules into hydrogen (which would leave the planet) and oxygen, which is still present.
D.
It would have soaked into the porous surface of Mars.


157.
What is the interior structure of Saturn?
A.
a thick mantle of liquid hydrogen with a rocky core and a relatively thin, gaseous atmosphere
B.
a thick, gaseous atmosphere over a thin mantle of liquid hydrogen and a rocky core
C.
a large, rocky core with a very thin mantle of liquid hydrogen and a thin, gaseous atmosphere
D.
a large liquid hydrogen core overlain by a thin, gaseous atmosphere


158.
What material produces the distinct red color of Mars?
A.
reddish vegetation which seems to fluctuate seasonally, particularly near the equator
B.
scattered sunlight from very fine dust, similar to sunset effects upon Earth
C.
atmospheric CO2, because it absorbs blue and green light preferentially
D.
rust or iron oxides


159.
In which of the following ways are Venus and Mars alike, yet are both markedly different from Earth?
A.
Their surface temperatures are both much higher than that of Earth.
B.
They are both perpetually shrouded in clouds.
C.
They both have either active or extinct volcanoes on their surfaces.
D.
Their atmospheres are made up primarily of carbon dioxide.


160.
The aphelion (farthest distance from the Sun) of a comet's orbit
A.
are all located far beyond the orbit of Pluto.
B.
are all closer to the Sun than the orbit of Pluto.
C.
are mostly confined to the region between Mars and Jupiter, although some have orbits reaching well beyond Pluto.
D.
can be located anywhere from inside the orbit of Pluto to as far as 100,000 AU from the Sun.


161.
Which one of the following four statements applies to all four of the Jovian planets?
A.
Liquid metallic hydrogen makes up a large part of their interiors.
B.
Their spin axes are approximately perpendicular to their orbital planes.
C.
They are almost entirely hydrogen and helium—only about 1% of the planet's mass is made up of heavier elements.
D.
They are all thought to have a substantial rocky core.


162.
Which of the following processes has played the greatest role in shaping the surface of the Moon?
A.
erosion by wind and atmospheric gases
B.
impacts of interplanetary bodies of all sizes
C.
motions of tectonic plates, producing mountain ranges wherever they collide
D.
recent volcanic activity, producing large numbers of crater-like volcanic calderas


163.
The lighter-colored bands that encircle the high atmosphere of Jupiter and are visible through telescopes from Earth are known as
A.
belts.
B.
white spots.
C.
rings.
D.
zones.


164.
Mars has a crust which is everywhere thicker than Earth's crust. What is the primary reason for this?
A.
Mars, being smaller, cooled more rapidly.
B.
Mars is cooler because it is farther from the Sun.
C.
Mars rotates too slowly to allow the crust to remain fluid.
D.
Mars rotates too rapidly to allow the crust to remain fluid.


165.
Tectonic activity on Venus is characterized by
A.
large-scale convection currents in the mantle, which push several hard, lithospheric plates around on the surface.
B.
constant resurfacing of the crust by lava floods, without separately identifiable upward and downward-flowing magma currents in the mantle.
C.
a cool, solid mantle that has not driven any crustal deformation for the last 3.2 billion years.
D.
hot-spot volcanism and localized regions of downwelling magma.


166.
Other than hydrogen and helium, the major components of the atmospheres of Jupiter and Saturn have been found to be
A.
H2O (water) and CO2 (carbon dioxide).
B.
N2 (nitrogen), O2 (oxygen), and CO2 (carbon dioxide).
C.
dust and iron oxides.
D.
CH4 (methane), NH3 (ammonia), and H2O (water).


167.
Most of the craters on the Moon were created by
A.
debris flying out to the Moon from asteroid impacts on Earth.
B.
volcanic activity during the early part of the Moon's history which left old calderas.
C.
impacts of fragments of asteroids more or less evenly and continuously over the history of the Moon.
D.
impacts of rocky debris during the first billion years of the Moon's history.


168.
A mare on the Moon is a
A.
large crater with a central peak terracing along the crater walls.
B.
crater shaped like a horse.
C.
large area of dark material on the lunar surface.
D.
large area of light material on the lunar surface.


169.
Which of the following statements is a correct description of the rotation of Earth?
A.
The average length of a day varies unpredictably from one year to the next because of the combined effects of solar and lunar tides.
B.
The average length of a day is gradually getting longer because Earth's rate of rotation is slowing down.
C.
The average length of a day is constant from year to year because nothing can change the speed of rotation of Earth.
D.
The average length of a day is gradually getting shorter because Earth's rate of rotation is speeding up.


170.
Jupiter's Great Red Spot
A.
has remained virtually unchanged during the three and a half centuries it has been observed.
B.
has disappeared (for decades at a time) and then re-emerged several times in the past three and a half centuries.
C.
has changed color dramatically more than once, becoming white or brown.
D.
has changed its size significantly during the past three and a half centuries.


171.
How are the relative ages of the different types of terrain on Ganymede estimated?
A.
The lighter the coloration, the older the terrain.
B.
The colder the surface, the older the terrain.
C.
The denser the cratering, the older the terrain.
D.
The smoother the surface, the older the terrain.


172.
The Roche limit around a planet is defined as
A.
the distance beyond which the orbital velocity of a body in a Keplerian orbit is greater than the escape velocity and matter is no longer captured by the planet.
B.
the distance inside which a solid satellite (e.g., a fragment of rock) will be pulled apart by tidal forces.
C.
the outer extent of the magnetic field of the planet, or the magnetospheric boundary.
D.
the distance inside which relative tidal forces will overcome the mutual gravitational forces of a group of particles.


173.
The surface of Europa, one of the Galilean moons of Jupiter, appears to be covered with
A.
dark areas of older crust separated by lighter, grooved terrain.
B.
many ancient craters and maria.
C.
rugged mountain ranges and ancient volcanoes.
D.
a smooth layer of ice, crossed by many cracks.


174.
The number of times that a typical comet can pass close to the Sun (i.e., the number of orbits that the comet can complete) before it completely vaporizes is between
A.
10,000 and 50,000.
B.
1 and 5.
C.
10 and 25.
D.
100 and 200.


175.
Which of the following statements is not true for asteroids?
A.
The total mass of all asteroids is much smaller than the mass of a planet like Earth.
B.
Some asteroids occupy the same orbit as Jupiter.
C.
Some asteroids pass closer to the Sun than Earth's orbital distance.
D.
A minority of all asteroids are in the asteroid belt.


176.
Which planets rotate about their axes in a retrograde direction, opposite to their orbital directions?
A.
Mercury and Neptune
B.
Venus and Neptune
C.
Venus and Uranus
D.
Mercury and Uranus


177.
The particles in Saturn's rings
A.
move in circular orbits, with the outer particles moving fastest because they are farthest from the planet.
B.
all move as if they are one solid disk.
C.
revolve in different directions depending on the distance from the planet.
D.
move in circular Keplerian orbits, the inner particles moving fastest.


178.
What is the relationship between the Kirkwood Gaps in the asteroid belt and the Cassini and Enke divisions in the rings of Saturn?
A.
Both are caused by large objects passing through swarms of smaller objects, sweeping out gaps in the swarms.
B.
Both were discovered by observers from the same group—Kirkwood and Enke worked at the Cassini Observatory.
C.
Both are caused by selective melting of material at these specific locations from the central radiating body, the Sun and Saturn respectively.
D.
Both are caused by disruptions of orbits of small objects by a larger object whose orbital period is a simple ratio of that of the small objects.


179.
The most active volcanic object in the Solar System is
A.
Earth, with many continuously active volcanoes and numerous earthquakes.
B.
Io, the inner Galilean moon of Jupiter.
C.
Venus, its high surface temperature indicating molten lava while its cloud cover is made up of volcanic gases.
D.
The Moon, where volcanism is causing many new craters per year.


180.
If viewed from a point directly above the plane of the planetary system, how would the Moon appear to rotate on its axis?
A.
It would rotate once per year as Earth and Moon orbit the Sun together.
B.
It would not rotate at all, because we always see the same face on Earth.
C.
It would rotate once per day, to maintain its direction toward Earth.
D.
It would rotate once per month, or once per revolution about Earth.


181.
Which of the following biochemical materials has been found and identified in rocks recovered from outer space (e.g., meteorites)?
A.
viruses
B.
living cells
C.
lichens and mosses
D.
amino acids


182.
In view of Mars's tilted angle of rotation at 25° to the ecliptic, its very similar rotation period to that of Earth (24 hours, 37 minutes), and its orbital period of nearly 2 years, what will be the seasonal variations on Mars, compared to those upon Earth?
A.
very similar seasonal variations, but each season lasting about half as long as those upon Earth because of the different orbital periods
B.
very similar seasonal variations, including seasons lasting about as long as those upon Earth because of the similar rotation rates of the two planets
C.
very similar seasonal variations, but with each season lasting twice as long as Earth's seasons
D.
much smaller seasonal variations than Earth's seasonal variations because of Mars's distance from the Sun, each season lasting about twice as long as those upon Earth


183.
The rings of Uranus
A.
were predicted theoretically because of the planet's similarity to Saturn.
B.
were first discovered while observing the occultation of a star by the Uranian system.
C.
were first discovered by Voyager 2 on its flyby in 1986.
D.
were first observed by Galileo.


184.
Moonquakes occur most often when the Moon is near perigee. The reason for this is
A.
increased tidal distortion of the Moon by Earth.
B.
the higher probability of impacts on the Moon of meteoroids that have been accelerated by Earth at these lunar phases.
C.
increased speed of rotation of the Moon at these times and the consequent reduction of the gravitational force on the surface.
D.
increased sunlight on the Moon's surface at these times.


185.
Triton, the giant moon of Neptune, differs from all other major moons of planets in that
A.
its orbit is very elliptical.
B.
its orbit lies inside the rings of Neptune.
C.
it orbits in a retrograde way, opposite to the planet's rotation.
D.
its orbit takes it over the planet's poles.


186.
At what point in its orbit does Jupiter appear to be brightest when viewed from Earth?
A.
opposition
B.
Its brightness does not vary with orbital position because of its almost circular orbit.
C.
conjunction
D.
when Earth-Jupiter line is at a right angle to the Sun-Jupiter line


187.
Which of the following effects is now thought to be the most likely cause for the inclinations of the spin axes of several of the planets, such as Uranus (and even Earth), to the perpendicular of their orbital planes?
A.
an out-of-balance force on the irregular mass distributions of planets from their moons, some of which have significant masses
B.
a small but steady force on one hemisphere of the planet from the highly directional solar wind
C.
a major collision with another planet-like body
D.
tidal distortion and deflection caused by neighboring planets


188.
Which of the moons of the giant planets is known to have a significant atmosphere?
A.
Titan, a moon of Saturn
B.
Callisto, a moon of Jupiter
C.
Triton, a moon of Neptune
D.
Europa, a moon of Jupiter


189.
How is the Io plasma torus formed?
A.
Io's motion through Jupiter's magnetosphere creates currents of electrons and charged particles in a loop between Io and Jupiter's north and south magnetic poles.
B.
Io disturbs Jupiter's magnetosphere, causing magnetospheric charged particles to collect in a ring around Io's orbit.
C.
Charged particles from Jupiter's magnetosphere ionize and eject atoms from Io's surface and from its volcanic plumes.
D.
Io's volcanic plumes propel neutral atoms into orbit around Jupiter, where they are then ionized by high-energy charged particles in Jupiter's magnetosphere.


190.
The plumes that were seen to rise from the surface of Triton, Neptune's largest satellite, are believed to be
A.
sulfur dioxide from geysers heated by tidal stresses.
B.
volcanic ash from eruptions similar to, but much smaller than, an Earth-bound eruption.
C.
water, methane, and ammonia ice crystals above volcanic vents.
D.
dark material projected upward by nitrogen gas released from sunlight or by undersurface heating.


191.
The surface temperature of Titan, the largest moon of Saturn, is
A.
368 K (+95°C).
B.
273 K (0°C).
C.
178 K (195°C).
D.
95 K (–178°C).


192.
How many moons of Jupiter were seen by Galileo?
A.
12
B.
None—he was unable to see them with the naked eye.
C.
4
D.
1


193.
The rings of Saturn are composed of very many small particles because
A.
they are made up of ice and ice-coated rocks, which break up easily in sunlight.
B.
they are inside the Roche limit of Saturn, where tidal forces are stronger than the mutual gravitational forces between particles.
C.
they were formed by the impact of a fast-moving asteroid on a large moon, which broke up into very many pieces.
D.
they were spun out of the planet under its rapid rotation over a long period of time.


194.
What observations of the Martian surface led Lowell to the conclusion that intelligent life forms existed upon Mars?
A.
lakes and rivers of water flowing from polar icecaps, detected by strong specular reflection of sunlight
B.
melting icecaps, a network of linear features that look like canals, and varying dark surface markings, assumed to be vegetation
C.
sculpted mountains in the shape of humanoid heads, obviously (to him) carved to indicate the presence of intelligent life to distant observers
D.
geometrical structures and patterns, which he interpreted as the remains of buildings and cities


195.
Io would probably be less active geologically if
A.
its orbit were circular.
B.
it were closer to Jupiter.
C.
Europa and Ganymede were closer to it.
D.
Jupiter did not rotate at such a high rate.


196.
What does Uranus look like from space?
A.
perpetually covered with yellowish, sulfur-rich clouds
B.
blue-green and featureless
C.
blue-green with white, high-altitude clouds, and dark storms
D.
reddish belts and light zones, parallel to the equator


197.
Three of the Galilean moons of Jupiter have orbital periods which are in the ratio 1:2:4. The Galilean moon which does not have such a relationship is
A.
Io.
B.
Europa.
C.
Ganymede.
D.
Callisto.


198.
What are the most common shapes of lunar craters and why?
A.
round, because the shock wave from the impact that produced them spread out uniformly in all directions
B.
random shapes, because mantle convection has deformed the surface and distorted the craters since their production by impacts of meteoroids
C.
all shapes from round to long and thin, depending on the angle at which the projectile hit the surface
D.
round, because most of the craters were produced by volcanic explosions which formed calderas, not by meteoroid impacts


199.
The surface of Ganymede, a Galilean satellite of Jupiter, is characterized by
A.
dark areas of ancient terrain and bright, younger, but still very old areas with many folded ridges indicating tectonic activity on Ganymede in the distant past.
B.
multicolored deposits of sulfur and sulfur compounds, with several lava lakes and active volcanic plumes.
C.
dark areas of ancient terrain, and bright areas with almost no craters and many signs of recent tectonic activity such as fracturing, creation of ice rafts and eruptions of icy lava.
D.
bright, eroded and ancient terrain broken by darker and younger areas which show signs of tectonic activity in the past, such as water or slush volcanoes and faulting along subduction zones.


200.
The existence of the Great Red Spot of Jupiter has been known since
A.
the 1600s.
B.
the first fly-by of a spacecraft, Pioneer 10, in December, 1973.
C.
the arrival at Jupiter of Voyager 1 with its imaging cameras in 1979.
D.
first light at the 200-inch telescope on Mt. Palomar in 1948.


201.
The dark-colored belts on Jupiter are brighter than the surrounding regions when viewed in infrared or heat radiation because
A.
chemical reactions causing the dark, visible colors also release energy and heat these regions.
B.
these regions are composed of hot dust and gases released from volcanoes and distributed around the planet by high winds.
C.
these regions are higher in Jupiter atmosphere, receive more sunlight, and hence are hotter in IR radiation.
D.
these regions are deeper and therefore hotter layers of gas in Jupiter's atmosphere.


202.
An explanation for the retrograde rotation (in a direction opposite to that of most other planets) of Venus which has received serious consideration is the
A.
frictional drag of its very dense atmosphere on the rotating planet throughout its history.
B.
uneven pull of the Sun's gravitation due to the oblate shape of the Sun.
C.
frictional slowing-down and eventual reversal of Venus's rotation by tidal forces at a time when the planet had deep oceans over its surface.
D.
combined gravitational effects of its neighboring planets, Mercury and Earth.


203.
The tail of a comet
A.
is longest when the comet is farthest from the Sun, because then it is unaffected by sunlight.
B.
is longest when the comet is closest to the Sun.
C.
remains constant throughout its complete orbital path.
D.
is longest when the comet is within the powerful gravitational field of Jupiter.


204.
Extensive volcanic activity observed on Jupiter's satellite Io is caused by
A.
tidal stresses from Jupiter and the other Galilean moons.
B.
“primordial” heat remaining from the release of gravitational energy during Io's formation.
C.
frictional heating between the moon's mantle and crust during plate movement, driven by convection.
D.
heat released by radioactivity in Io's core and mantle.


205.
Moonquakes
A.
never occur; the Moon is seismically quiet.
B.
occur but are much weaker and much less frequent than earthquakes.
C.
are much more violent and occur much more often than earthquakes.
D.
occur, but only from the impact of meteoroids from space.


206.
The reason why the individual particles within Saturn's rings have not combined together by mutual gravitational attraction to form one or two moons is that
A.
the gravitational force from the Sun is sufficient to prevent coalescence.
B.
tidal distortion forces from the planet are greater than the mutual gravity between the particles.
C.
the excess heating from Saturn has melted the ice on the rocks so that the rocks will no longer stick together.
D.
they are moving too fast to stick together even if they bump into one another.


207.
The one terrestrial planet that rotates in the “wrong” direction (opposite to the planet's direction of revolution around the Sun) is
A.
Mars.
B.
Earth.
C.
Venus.
D.
Mercury.


208.
Does Mars have a planet-wide magnetic field?
A.
yes
B.
No, because the rotation rate is too slow to produce the necessary electric currents.
C.
No, because the core is solid, not liquid.
D.
No, because the core, although a liquid mixture of iron and sulfur, does not support electric currents.


209.
Most of the craters on the Moon are thought to have been caused by
A.
the intense bombardment by large and small bodies over an early and specific period in the Moon's history.
B.
volcanic activity, leaving behind volcano craters similar to those on Earth.
C.
the continuous bombardment throughout the Moon's life, including the present and recent past, by large and small asteroids.
D.
the collapse of volcanic domes, leaving central peaks in the craters.


210.
Which planet has its spin axis tilted 98° from the perpendicular to its orbital plane?
A.
Mercury
B.
Neptune
C.
Venus
D.
Uranus


211.
The Barringer meteorite crater is located in
A.
Iceland.
B.
Australia.
C.
Siberia.
D.
Arizona.


212.
The rotation periods for the Jovian planets—Jupiter, Saturn, Uranus, and Neptune—are
A.
very short—between 1 and 2 hours.
B.
very long—on the order of years because of the sizes.
C.
very short—about 10 to 20 hours.
D.
reasonably long—on the order of several Earth days.


213.
What is the average distance between asteroids?
A.
about three times the length of a football field
B.
about twice the diameter of Earth
C.
about half the distance between Earth and the Moon
D.
about twice the distance between Earth and the Moon


214.
Io, one of the major Jupiter moons, is undergoing extensive volcanic activity associated with interior heating that is caused by
A.
original heat, caused by gravitational condensation at the moon's formation.
B.
solar radiation and heat falling on the surface.
C.
the impact of Jupiter's Van Allen particles on Io's surface.
D.
tidal distortion, and internal friction because of flexing.


215.
Why is the Moon in a synchronous orbit around Earth, always keeping the same face toward Earth?
A.
There is a strong magnetic attraction between the two bodies which keeps the Moon turned toward Earth.
B.
The Moon must rotate on its axis at the same rate it orbits Earth to conserve angular momentum.
C.
As the Moon rotates, friction between the Moon's large liquid interior and its mantle has slowed the rate of rotation until it just matches the orbital rate. Over time it will slow further, and then the Moon will no longer be in a synchronous orbit.
D.
When the Moon was molten and experienced chemical differentiation, the gravitational pull of Earth caused the iron core to form off-center. Now Earth pulls harder on that core, causing it always to face Earth.


216.
We have studied asteroids by all of the following methods except one. Which is the exception?
A.
sending radar pulses to reflect off the surface and analyzing the result
B.
watching the variations in the sunlight reflecting off the asteroids
C.
sending a spacecraft to orbit an asteroid
D.
landing a robot rover to survey an asteroid


217.
What is the primary cause of moonquakes?
A.
the collision of tectonic plates
B.
meteoroid impact
C.
tidal forces due to the gravitational pull of Earth
D.
tidal forces due to the gravitational pull of the Sun


218.
Examination of the whole surface of the Moon shows us that
A.
craters exist only on one side of the Moon.
B.
the Moon appears to have two distinctly different sides, that seen from Earth and that hidden from Earth.
C.
surface features are distributed uniformly over the whole Moon.
D.
the northern hemisphere is distinctly different from the southern hemisphere.


219.
Saturn is less massive than Jupiter but has almost the same size. Why is this?
A.
Saturn's interior is hotter than that of Jupiter.
B.
Saturn is composed of lighter material than is Jupiter.
C.
Saturn is rotating faster than Jupiter, and the increased centrifugal force results in a larger size.
D.
The smaller mass exerts less gravitational force and is unable to compress the mass as much as in Jupiter.


220.
What is the origin of the majority of lunar craters?
A.
impacts by space probes
B.
surface collapse after loss of groundwater by evaporation
C.
volcanic explosions
D.
impacts by meteoric material


221.
On a time-exposure photograph of the sky as it orbited the Sun, how would a typical asteroid appear if the camera were tracking the background stars?
A.
It would look like a small, diffuse patch against the sharp images of stars because of the dust and gas surrounding it.
B.
It would produce a flash of light as it crossed the field of view of the camera.
C.
It would look like any other star, a small extra dot not shown on star charts of this area of the sky.
D.
It would produce a short trail as it moved slowly against the background stars.


222.
The tilts of the equators of Uranus and Neptune to their respective orbital planes are
A.
almost zero for both planets.
B.
very similar—each about 45°.
C.
very similar—at a large angle, near 90°.
D.
very different.


223.
Water has been discovered on Mars. What form does it take?
A.
only as atmospheric water vapor, never condensing out as liquid water or solid ice
B.
as a liquid, flowing continuously along the numerous flood valleys and meandering stream beds
C.
in permafrost, polar icecaps, and atmospheric vapor
D.
as a liquid in lakes and rivers


224.
The material in the Uranus ring system differs from that in the Saturn ring system in what important way?
A.
The individual particles move as a solid ring for some reason, not in Keplerian orbits as do the Saturnian ring particles.
B.
The particle sizes are larger, those of the Saturnian system being only snowflake or dust grain sizes.
C.
It reflects much more sunlight than that of the Saturn ring material.
D.
It reflects much less sunlight than does the material of Saturn's rings.


225.
What is the relationship between the orbital periods of the four Galilean satellites of Jupiter?
A.
1:2:4:8—Europa takes twice as long to orbit Jupiter as Io, Ganymede takes twice as long as Europa, and Callisto takes twice as long as Ganymede.
B.
1:2—Europa takes twice as long to orbit Jupiter as Io, but there is no simple integer relationship between Callisto, Ganymede, and Europa.
C.
The periods appear to be random, with no simple relationship between them.
D.
1:2:4—Europa takes twice as long to orbit Jupiter as Io, and Ganymede takes twice as long as Europa, but there is no simple integer relationship between Callisto and Ganymede.


226.
The Moon has
A.
a global magnetic field which deflects the solar wind, but is not strong enough to trap high-energy charged particles.
B.
no global magnetic field, although weak magnetism in lunar rocks does show that a magnetic field existed earlier in the Moon's history.
C.
no detectable magnetism of any kind, either global or in individual rocks.
D.
a very weak global field which is not strong enough to deflect the solar wind before it hits the lunar surface.


227.
When we view Mars at its most favorable opposition, a Martian would view Earth at
A.
most favorable opposition.
B.
least favorable opposition.
C.
superior conjunction.
D.
inferior conjunction.


228.
We believe the rate of bombardment of projectiles striking bodies in the inner solar system decreased steadily except for a sharp increase between 3.8 and 4.0 billion years ago. What is believed to be the cause of this increase?
A.
The Sun flared up and disturbed the entire solar system.
B.
The planet which once existed between the orbits of Mars and Jupiter was torn apart leaving the asteroid belt and much new debris to bombard the inner planets.
C.
Jupiter and Saturn were moving to their present orbits, and their gravitational fields disturbed the asteroid belt and sent many objects into the inner solar system.
D.
The star Proxima Centauri (still the closest star to the Sun) passed close to the solar system and pulled many of the asteroids out of their orbits.


229.
What is the status of the greenhouse effect on Mars at the present time?
A.
It no longer exists at all.
B.
It is very weak and raises the planet's temperature only a few degrees above the temperature it would have with no atmosphere at all.
C.
It is weak but becoming stronger as Martian volcanoes continue to dump large amounts of CO2 into the atmosphere.
D.
It is very strong and has caused the temperature to be at least 100 degrees above the temperature it would have been with no atmosphere at all.


230.
The following planets and satellites of planets are, in increasing order of size (with Europa being one of the major moons of Jupiter),
A.
Moon, Europa, Mars, Mercury.
B.
Mercury, Moon, Europa, Mars.
C.
Europa, Mercury, Moon, Mars.
D.
Europa, Moon, Mercury, Mars.


231.
A meteor shower, the appearance of greater than average numbers of “shooting stars” at a particular time in the year from a specific direction in the sky, is related to which astronomical phenomenon?
A.
Earth's passage through different parts of the spiral arms of the galaxy
B.
the passage of Earth through the remnants of an old comet
C.
the passage of Earth through intense streams of solar material, including dust particles, during regular solar activity
D.
Earth's passage through part of the asteroid belt


232.
The Cassini division is
A.
a major division in the rings of Saturn that is visible from Earth.
B.
a gap between two mountain ranges on the Moon.
C.
the division between terrestrial and Jovian planets.
D.
a gap between two groups of asteroids in the asteroid belt.


233.
Taken over the entire surface of the Moon, the older, lighter-colored and heavily cratered highlands (terrae) take up
A.
more than 4/5 of the lunar surface.
B.
between 1/3 and 1/2 of the lunar surface.
C.
less than 1/5 of the lunar surface.
D.
between 1/2 and 3/4 of the lunar surface.


234.
The most common meteorites to hit Earth are
A.
the stony meteorites.
B.
the carbonaceous chondrites.
C.
the iron meteorites.
D.
the stony-iron meteorites.


235.
Which planet has among its satellites one large moon, which orbits in a retrograde direction, and one moderate-sized moon with a highly elliptical orbit?
A.
Uranus
B.
Saturn
C.
Neptune
D.
Jupiter


236.
What is the physical appearance of Jupiter as seen from Earth or a spacecraft?
A.
a series of dark belts and light zones parallel to the equator
B.
a uniform bluish color with a high-level haze
C.
v-shaped cloud forms around the equator, indicative of rapid winds
D.
uniform red-colored dust clouds over cratered surface


237.
Which property of Triton, a moon of Neptune, makes it significantly different from all other major moons in the Solar System?
A.
Its orbit is at right angles to the equator of its mother planet.
B.
It has an extremely dark, smooth surface and consequently was not discovered until very recently.
C.
It orbits in a direction opposite to most other moons and opposite to the normal direction of planetary rotation and revolution.
D.
It has an atmosphere of nitrogen and oxygen, with H2O clouds.


238.
A piece of rock from outer space that reaches Earth's surface after surviving a fiery passage through Earth's atmosphere is known as
A.
a meteoroid.
B.
a meteor.
C.
a meteorite.
D.
an asteroid.


239.
If the orbital period of Uranus is 84 years and its rotational period is about 17 hours, how often will the Sun shine vertically on the north pole ?
A.
never, because of the extreme tilt of the spin axis to the ecliptic plane
B.
once every 42 years
C.
once every 17 hours
D.
once every 84 years


240.
The Great Red Spot is
A.
a large, long-lived, high-pressure storm in Jupiter's atmosphere.
B.
the colored polar cap of Jupiter.
C.
clouds of dust-laden gas upwelling above the top of a massive mountain or a volcano on the planet's surface.
D.
a type of storm in Jupiter's atmosphere that can last for a few months at a time before disappearing.


241.
The period and direction of rotation of Mars are
A.
about twice as long as Earth's period, about 48 hours, in the same direction as Earth.
B.
a little longer than one Earth day, in the opposite direction to Earth.
C.
about 240 days, in the opposite direction to Earth.
D.
a little longer than 24 hours, in the same direction as Earth.


242.
Moonquakes occur
A.
most often at full moon, not at new or quarter moons.
B.
most often when the Moon is near perigee.
C.
randomly at all times, at a uniform rate.
D.
most often when the Moon is near apogee.


243.
The brown ovals seen in Jupiter's atmosphere are
A.
upwelling ammonia and methane gas which condenses to form clouds in the cold upper atmosphere.
B.
vortices of a similar nature to the Great Red Spot, but smaller and with shorter lifetimes.
C.
ammonia ice crystals over high-pressure systems.
D.
holes in Jupiter's cloud cover, through which we can see deeper layers of the atmosphere.


244.
The expected (and now measured, at least for Halley's Comet) size of the nucleus of a typical comet is about
A.
106 km.
B.
107 km.
C.
10 km.
D.
100 m.


245.
Moonquakes occur
A.
at a rate of about 3000 per year, less than the rate of terrestrial earthquakes.
B.
at a similar rate to quakes on Earth, hundreds of thousands per year.
C.
at a rate of only a few per year.
D.
only very rarely; the Moon is almost seismically quiet because it has no molten core.


246.
One of the most important sources of heat in the interiors of moons that orbit close to giant planets is
A.
reflection of sunlight from the planet's surface onto the moons.
B.
continuous tidal distortion from other moons and the planet.
C.
absorption of thermal radiation from the planet.
D.
decay of radioactive elements within the moons.


247.
Comets that we find in the Kuiper belt are believed to have formed
A.
in the inner Solar System. Sunlight, and the solar wind acting over billions of years, have pushed them out past the orbit of Pluto.
B.
in elliptical orbits extending out to tens of thousands of AU, and gravitational interactions with the giant planets have circularized their orbits into a band beyond Pluto.
C.
exactly where we see them now, in a band beyond the orbit of Pluto.
D.
between the orbits of Jupiter and Neptune. They were flung out beyond Pluto by gravitational interactions with the giant planets.


248.
Which scientific method was used to make the initial discovery of the rings around Uranus?
A.
spacecraft exploration of the planet
B.
direct photography from Earth
C.
X-ray photography from space
D.
occultation of a star as the planet and rings moved in front of it


249.
Much of the water on Earth, Venus, and Mars has come from outgassing of water vapor from volcanoes. Much of the remainder is believed to have come from
A.
chemical reactions which have produced water from more complex molecules.
B.
the combination of elemental hydrogen and oxygen in the atmosphere, the reaction powered by high energy ultraviolet rays.
C.
baking of rocks containing water.
D.
the impacts of comets.


250.
The Kirkwood Gaps (see Fig. 15-4, Freedman and Kaufmann, Universe, 8th ed.) are found in the
A.
equatorial region of the Sun.
B.
rings of Saturn.
C.
spectrum of hydrogen gas.
D.
asteroid belt.


251.
Jupiter's mass is more than 300 times the mass of Earth, and Saturn has almost one hundred times Earth's mass. These masses were determined by
A.
watching carefully the orbits of these planets around the Sun.
B.
measuring the deviations of the other planets from their expected orbits around the Sun.
C.
measuring the deflection of Halley's comet from its orbit when it is near Jupiter and Saturn.
D.
measuring the orbits of the satellites of these planets.


252.
What kind of orbits do the Trojan asteroids follow?
A.
circular orbits at the same distance from the Sun as Jupiter
B.
circular orbits at about 2.8 AU from the Sun
C.
long, elliptical orbits that cross that of Earth
D.
long, elliptical orbits ranging from Neptune's orbital distance to Jupiter's orbital distance


253.
What future awaits Triton, the largest satellite of Neptune?
A.
eventual escape from Neptune as it gradually spirals outward
B.
tidal breakup as it slowly spirals closer to Neptune
C.
probable destruction on impact onto Pluto
D.
gravitational capture by Pluto


254.
Suppose an intense meteor shower occurs on a certain date this year, but there was no shower last year on that date, and it turns out that there is no shower next year on that date. A likely explanation is that
A.
this year Earth passed through the orbit of a recently disintegrated comet, one for which the debris is not yet distributed along the entire orbit.
B.
a small comet has passed through Earth's atmosphere.
C.
the meteor shower is the remnant of a comet that had a semimajor axis larger than one AU and a period longer than one year.
D.
the debris along the orbit was mostly fine dust, which has been blown away by the solar wind.


255.
Europa, one of the Galilean satellites of Jupiter, has a surface consisting of
A.
rock, heavily cratered like the highlands of our Moon.
B.
an ancient, icy crust covered with numerous craters; no surface cracks or groove belts that would indicate internal activity.
C.
a relatively young, icy crust covered with a network of streaks and cracks, and only a few impact craters.
D.
an icy crust showing two interlocking types of terrain, one ancient and heavily cratered, the other younger with systems of parallel grooves.


256.
The most common surface features on Venus are
A.
ancient river valleys and huge floodplains.
B.
impact craters.
C.
volcanoes and lava flows.
D.
evidence of plate tectonic motion, including long mountain ranges and subduction troughs.


257.
The three-dimensional shape of Jupiter is
A.
a sphere but with extended radius near the belts and zones, within +/–10° of the planet's equator.
B.
an oblate spheroid with its spin axis shorter than its equatorial diameter because of its rapid spin.
C.
almost a perfect sphere because of its fluid physical structure.
D.
a prolate spheroid with its spin axis longer than its equatorial diameter because of its rapid spin.


258.
The major planet whose spin axis lies almost in its orbital plane is
A.
Neptune.
B.
Mercury.
C.
Uranus.
D.
Mars.


259.
What gives Uranus its blue-green coloration?
A.
absorption of blue and green sunlight by ammonia gas
B.
emission of spectral lines in the blue and green by ethane and propane, excited by solar UV radiation
C.
continuous emissions from auroras in the upper planetary atmosphere
D.
absorption of the red sunlight by methane gas


260.
On which other world in the Solar System do we find evidence of ice rafts (now apparently frozen) similar in many respects to ice rafts in the Arctic Ocean?
A.
in the tropical regions of Saturn's satellite Titan
B.
on Pluto, in the equatorial region facing most directly toward the Sun
C.
on Mars, at the edges of the polar caps
D.
in the icy surface of Jupiter's satellite Europa


261.
Why are the lunar maria concentrated almost entirely on the near side of the Moon?
A.
The apparent concentration of maria on the near side is merely an illusion caused by the fact that the near side is the only side that we can see.
B.
The crust is thicker on the far side of the Moon, restricting massive lava flows after asteroid impact.
C.
Earth's gravity concentrated asteroid impacts on the near side of the Moon.
D.
Earth's gravity has concentrated meteoroid impacts on the far side of the Moon, erasing the ancient, smooth lava plains.


262.
The major gaps in the rings of Saturn are most likely caused by
A.
mutual gravitational interactions between the multitude of particles in the rings.
B.
the major moons of Saturn, which move in these gaps and sweep out the ring material.
C.
the intervention of a massive body, which moved through the rings in their early history, leaving the gaps.
D.
the combined gravitational forces of Saturn and its major moons, which deflect the paths of particles which stray into the gaps.


263.
People on Earth see
A.
only the sunlit side of the Moon.
B.
the same side of the Moon at all times.
C.
the entire Moon once each month as it rotates.
D.
the entire surface of the Moon once per year as Earth revolves around the Sun.


264.
Which chemical or chemicals appear to play a prominent role in the eruptive plumes of Io?
A.
methane and ammonia
B.
molten lava
C.
sulfur and sulfur dioxide
D.
water and steam


265.
What appears to have caused the extensive cracking and streaking of the surface of Europa?
A.
tidal flexing by Jupiter
B.
shrinking of the satellite as it cooled
C.
impacts by cometary debris
D.
expansion of the surface as the ice froze


266.
Other than the rings, how does the appearance of Saturn differ from that of Jupiter?
A.
There are belts and zones on Saturn, but they are very faint and hazy compared to Jupiter's.
B.
Saturn's visible surface is basically featureless, with no hint of the belts and zones of Jupiter.
C.
Saturn shows an ever-changing system of dark storms and light eddies, without the belts and zones of Jupiter.
D.
Saturn has many more belts and zones than Jupiter, with large storms distorting their shapes.


267.
Ganymede, one of the Galilean satellites of Jupiter, has a surface consisting of
A.
rock, heavily cratered like the highlands of our Moon.
B.
an icy crust showing two interlocking types of terrain, one ancient and heavily cratered, the other younger with systems of parallel grooves.
C.
an ancient, icy crust covered with numerous craters; no surface cracks or groove belts that would indicate internal activity.
D.
a relatively young, icy crust covered with a network of streaks and cracks and only a few impact craters.


268.
The structure of Ganymede, a Galilean satellite of Jupiter, is thought to be
A.
a thick crust of ice, a rocky mantle, and metallic core.
B.
about half rock and half ice, with the rock at the center and the ice outside.
C.
a large rocky core with a thin layer (100 km thick) of ice and water over it.
D.
mostly or entirely rock with no firm evidence of an iron core, but with active volcanoes on its surface.


269.
The heating of the interior of Io, the innermost Galilean moon of Jupiter, is caused by
A.
continual bombardment by meteoroids attracted by Jupiter's enormous gravitational pull.
B.
thermal heating from Jupiter, because Jupiter emits more radiation than it receives from the Sun.
C.
the fact that Io moves inside Jupiter's magnetosphere, where the temperature is as high as anywhere in the Solar System.
D.
continuous tidal distortion by Jupiter and the other moons.


270.
Why can permanent liquid water not exist on Mars today?
A.
Both atmospheric pressure and surface temperature are too low, and any water would be in the form of ice or vapor.
B.
The surface of Mars is too porous to allow water to remain on the surface.
C.
Water would react with the CO2 in the atmosphere to form carbonic acid, which would react quickly with the rocks on Mars to destroy the water.
D.
Surface temperatures are too high, since at the low Martian atmospheric pressure, water would just boil away at the present Martian temperatures.


271.
How old are the lunar maria?
A.
less than 1 billion years old
B.
1.8 to 2.6 billion years old
C.
3.1 to 3.8 billion years old
D.
4.0 to 4.3 billion years old


272.
Most astronomers feel that there are many additional large, icy bodies beyond the orbit of Pluto. Which of the following is not used as a major argument in favor of this hypothesis?
A.
comparison with observations of other Solar Systems
B.
multiple nature of the Pluto system
C.
retrograde orbit of Neptune's satellite, Triton
D.
abundance of craters observed on planets and moons in the outer Solar System


273.
The darker-colored bands that encircle the high atmosphere of Jupiter and are visible through telescopes from Earth are known as
A.
rings.
B.
white spots.
C.
belts.
D.
zones.


274.
When viewed from Earth, the apparent angular diameter of Jupiter varies with time because
A.
the distance between Jupiter and Earth varies.
B.
of tidal influence of the four massive moons of Jupiter.
C.
the fluid planet pulsates with a long natural oscillation period.
D.
Jupiter's gaseous atmosphere expands and contracts as the strength of sunlight varies because of the planet's elliptical orbit.


275.
The asteroid belt exists between the orbits of which planets?
A.
Mars and Jupiter
B.
Earth and Mars
C.
Jupiter and Saturn
D.
Venus and Earth


276.
The most massive planetary satellite in the Solar System is
A.
the Earth's Moon.
B.
Jupiter's satellite, Ganymede.
C.
Jupiter's satellite Europa.
D.
Saturn's satellite Titan.


277.
“Markings” on the surface of Saturn are
A.
of a completely different pattern from those on Jupiter and more distinct.
B.
nonexistent, because Saturn shows completely uniform cloud tops.
C.
similar in appearance to those on Jupiter but much less distinct.
D.
similar to those on Jupiter but much more pronounced.


278.
Where is the Cassini division found in our solar system?
A.
between two band systems on the visible “surface” of Jupiter
B.
between two major groups of asteroids in the asteroid belt
C.
between two major ring systems around Saturn
D.
between the terrestrial and the Jovian planets


279.
The polar caps on Mars are most likely made up of
A.
water and CO2 ices.
B.
light-colored dust blown there by intense dust storms and large dust devils.
C.
volcanic outflow of light-colored lava and dust similar to that produced by Earth-based volcanoes.
D.
sulfur dioxide and sulfur compounds.


280.
At what point in its orbit would Jupiter appear to be faintest when viewed from Earth?
A.
conjunction
B.
when the line from Earth to Jupiter is at a right angle to the line from Jupiter to the Sun
C.
Its apparent brightness does not vary with orbital position, because it has an almost circular orbit.
D.
opposition


281.
A comet's tail points
A.
toward the Sun because it is caused by jets of gases evaporated off the comet's nucleus by the heat of the Sun.
B.
back along the comet's orbit, and points away from the Sun while only the comet is approaching the Sun.
C.
toward Jupiter because of the its gravitational pull.
D.
away from the Sun regardless of the comet's motion.


282.
The Oort cloud of comets, which surrounds the Solar System at a distance of about 50,000 AU, is believed to be
A.
material flung out of the inner Solar System by the gravity of the newly formed giant planets early in the Solar System history.
B.
an interstellar cloud through which the Sun and planets happen to be passing, but which is not otherwise connected to the Solar System.
C.
debris left behind at that distance by the collapse of the interstellar cloud that formed the Sun and planets.
D.
material captured from interstellar space by the Sun's gravity.


283.
In what way do Uranus and Neptune differ from Jupiter and Saturn?
A.
Uranus and Neptune do not have observable magnetic fields.
B.
Uranus and Neptune apparently do not have rocky cores.
C.
The atmospheric winds of Uranus and Neptune are not parallel to the equator.
D.
Hydrogen and helium make up a smaller fraction of the total mass of Uranus and Neptune.


284.
On Earth (and in the past, on Mars), volcanoes have been vital for keeping the planet warm. This is because
A.
heat conducted from the molten mantle to the surface near volcanoes, where the crust is thin, is a major heat source for the atmosphere.
B.
heat released along the major rift zones is the biggest source of heating for the atmosphere.
C.
direct heat input by underwater volcanoes keeps the oceans from freezing.
D.
they have replenished the CO2 (a greenhouse gas) that is washed out of the atmosphere by rain.


285.
The clouds in the atmosphere of Venus consist primarily of
A.
dust particles.
B.
droplets of liquid methane and ammonia.
C.
droplets of H2SO4 or sulfuric acid.
D.
H2O.


286.
What feature of the Saturnian moon Enceladus makes it a unique object in our Solar System?
A.
It rotates about its axis about every 2 minutes.
B.
It passes through the planet's ring system every orbit on its highly elliptical path.
C.
It has the most reflective surface of all objects in the Solar System.
D.
It orbits its planet in a retrograde direction.


287.
The reason Venus has very few impact craters compared to the Moon is believed to be that
A.
lava flows have covered all but the most recent craters.
B.
Venus formed closer to the Sun than did the Moon, where the cratering rate was much lower.
C.
the surface of Venus is subducted back down into the mantle over periods of several hundred million years.
D.
erosion due to wind and rainfall has eroded away all but the most recent craters.


288.
Which of the following satellites of planets in our Solar System has a significant, dense atmosphere?
A.
Titan, a moon of Saturn
B.
the Moon, of Earth
C.
Triton, a moon of Neptune
D.
Io, a moon of Jupiter


289.
What features dominate the surface of Callisto, one of Jupiter's satellites?
A.
volcanoes, lava lakes, and sulfur dioxide frost
B.
cracks, streaks, and very few craters in an otherwise smooth, icy surface
C.
craters, densely spread over the entire surface
D.
old, dark and highly cratered polygons separated by younger, lighter, grooved terrain


290.
Most meteor showers occur when Earth moves through
A.
the orbit of a comet (or of a former comet).
B.
the Kuiper Belt.
C.
the Asteroid Belt.
D.
the Oort Comet Cloud.


291.
The Hawaiian Islands experience continuous volcanic activity because they
A.
lie right on a boundary between tectonic plates.
B.
happen to be at a focal point for seismic waves from earthquakes around the Pacific Ocean.
C.
are in the center of a major ocean.
D.
lie directly above a hot-spot plume in Earth's interior.


292.
Uranus and Neptune are about the same size, yet Neptune shows spots and bands in its atmosphere while Uranus is almost featureless. Why this difference?
A.
Uranus and Neptune are at vastly different distances from the Sun, and the resulting difference in temperature causes the atmospheres to behave very differently.
B.
The two planets, while of similar size, have atmospheres which differ vastly in composition.
C.
The difference can be traced to the fact that Uranus is lying with its rotation axis almost in the plane of its orbit and Neptune is not.
D.
Neptune is still contracting and giving out energy which warms the lower layers of its atmosphere while Uranus is not.


293.
It was originally thought questionable whether a manned lunar landing could take place because
A.
of the extreme temperatures on the lunar surface.
B.
the lunar surface might be too soft to land upon.
C.
of extreme levels of radiation from the decay of radioactive elements and the lack of a shielding atmosphere.
D.
the low atmospheric pressure would adversely affect human beings.


294.
What is the dominant circulation pattern in Jupiter's atmosphere (i.e., at the visible “surface”)?
A.
uniform eastward flow of the entire atmosphere, with occasional dark storms and turbulent swirls
B.
isolated storms and turbulent swirls, with little overall flow pattern in any particular direction
C.
alternating bands of eastward and westward flow parallel to the equator, with light and dark ovals between these flows
D.
air rising at the equator, flowing north and south toward the poles, then sinking and returning to the equator at a lower level


295.
Most of the craters on the Moon were formed by
A.
slumping of the surface following the outflow of lava from below the region.
B.
bombardment by interplanetary meteoritic material.
C.
wind and water erosion of mountains and hills in the distant past.
D.
volcanic action; the craters are the old calderas of volcanoes.


296.
Based on their average densities, the six moderate-sized satellites of Saturn are believed to be composed
A.
mostly of ice, with perhaps a small, rocky core.
B.
of about half rock and half ice.
C.
mostly of rock, with only a thin mantle of ice.
D.
mostly of liquid hydrogen.


297.
The best images of the overall topology of Venus have been produced by
A.
visible wavelength images from cameras on board an orbiting spacecraft.
B.
photography from the Hubble Space Telescope at UV wavelengths to which the Venus atmosphere and clouds are transparent.
C.
imaging cameras on board two spacecraft that soft-landed on the surface of Venus.
D.
reflection of microwave and short radio wave radiation from the surface by an orbiting spacecraft.


298.
Which of the following objects in the Solar System has the smoothest surface relative to its radius?
A.
Io, the volcanic moon of Jupiter, whose surface is continuously coated with volcanic material
B.
Earth, with its oceans and molten interior that both allow readjustment of the surface
C.
Mercury, in view of the intense solar radiation that has melted and smoothed the surface
D.
Europa, a moon of Jupiter coated with water ice


299.
If you were standing on the Moon with Earth in view, how much time would elapse between two successive “Earthrises”?
A.
about 1 synodic month
B.
about 1 day
C.
about 1 sidereal month
D.
infinite time, because the same side of the Moon always faces toward Earth


300.
The white spots observed in Saturn's atmosphere are believed to be crystals of
A.
ammonia.
B.
water vapor.
C.
methane.
D.
hydrogen.


301.
What are the most abundant gases in the atmosphere of Uranus?
A.
hydrogen and helium
B.
carbon dioxide and nitrogen
C.
nitrogen and ammonia
D.
methane and water


302.
Where are the asteroids located?
A.
Their orbits are distributed more or less uniformly throughout the Solar System.
B.
All asteroids have orbits between the orbits of Mars and Jupiter.
C.
Most asteroids have orbits between the orbits of Mars and Jupiter, but there are gaps caused by resonances with Jupiter.
D.
Most asteroids have orbits between the orbits of Mars and Jupiter, but there are gaps caused the motions of the largest asteroids moving through the asteroid belt and sweeping out regions much like the shepherd satellites in the rings of Saturn.


303.
If the orbits of one of the large moons were somehow deflected so that it passed within the Roche Limit of Jupiter it would be torn to pieces by tidal forces. However, there are many artificial satellites orbiting Earth within Earth's Roche Limit, and these are not torn apart. Why not?
A.
Earth's smaller gravity is insufficient to tear anything apart.
B.
The Roche Limit applies only to objects held together by gravity.
C.
Earth's rotation counteracts the tidal forces.
D.
The satellites are held in balance between Earth's gravity and the Moon's gravity.


304.
How would “Interplanetary Travel” advertise a holiday on Jupiter's satellite Io?
A.
Glaciers galore for your hiking pleasure under star-studded skies!
B.
Hot and dry—never rains—beautiful sulfurous skies!
C.
Exquisite ethane lakes, hydrocarbons beyond your wildest dreams!
D.
Largest number of volcanoes for your travel dollar anywhere in the Solar System!


305.
The northern Martian polar cap decreases in size during the northern Martian summer but does not completely disappear. What is the explanation for this?
A.
The polar cap is composed entirely of solid carbon dioxide (dry ice).
B.
The polar cap is composed partially of water ice.
C.
streams on the surface constantly keep the northern polar cap supplied with water during the summer.
D.
The Martian atmosphere can hold only so much water vapor from the melting ice cap before the atmosphere becomes saturated.


306.
The four Galilean moons of Jupiter do not all have the same mean density because
A.
heat from Jupiter prevented ice from forming at the locations of the inner moons.
B.
heat from the Sun prevented ice from forming in the outer part of the “Jovian Nebula,” from which the moons formed.
C.
the larger moons are more gravitationally compressed.
D.
the moons formed at different distances from the Sun and were later captured by Jupiter.


307.
The weak and variable magnetic field measured by the Galileo spacecraft on Europa is generated by
A.
its magnetized solid iron core.
B.
electrical currents between the moon and Jupiter, through the conducting magnetosphere.
C.
the motion of molten iron in Europa's core.
D.
electrical currents in the ocean water, induced by Europa's motion through Jupiter's intense magnetic field.


308.
The white ovals seen on Jupiter appear to be
A.
vortices (whirlpools) created between regions of oppositely directed winds.
B.
upwelling gas that then descends in the brown ovals.
C.
descending masses of gas within the dark belts.
D.
clouds of ammonia ice crystals that condense when Jupiter's atmosphere flows over fixed obstacles such as mountains.


309.
The ecliptic is the plane defining Earth's orbit around the Sun. The orbits of most other objects in the Solar System generally lie fairly close to the ecliptic. However, the orbits of which one of the following types of objects do not generally lie close to the ecliptic?
A.
large moons
B.
asteroids
C.
comets
D.
Jovian planets


310.
Does Neptune have rings orbiting the planet?
A.
no
B.
yes—one almost transparent ring composed entirely of fine dust particles
C.
yes—three very wide, bright rings and several faint, thin ones
D.
yes—a system of thin, dark rings of particles of methane ice


311.
The lunar maria appear smooth because they are
A.
ancient sea beds, now dry, dating back to when the Moon had a denser atmosphere and rainfall was abundant.
B.
recent lava flows, occurring within the last billion years, which have obliterated earlier craters.
C.
regions where craters have been obliterated by crustal deformation caused by hot spots and volcanic lava flow from the underlying molten mantle.
D.
ancient lava flows that occurred soon after the end of an early period of intense bombardment and have had relatively few impacts since then.


312.
Which of the planets fits the following description: “a solid, cool surface, with occasional dust clouds and a thin CO2 atmosphere”?
A.
Venus
B.
Jupiter
C.
Mars
D.
Mercury


313.
Which of the following Earth-bound phenomena do “volcanoes” on Io, the innermost Galilean moon of Jupiter, most resemble in behavior?
A.
undersea volcanoes, where hot lava produces explosive boiling of the water
B.
mountain volcanoes such as Mount St. Helens, exhibiting rare but devastating explosions throwing material high into the atmosphere
C.
lava-flow volcanoes occurring on the tops of mountains, such as those on Hawaii
D.
regularly spouting geysers in relatively flat hotsprings areas


314.
Seasonal variations at a particular point on Uranus during a Uranian year would be
A.
almost nonexistent, because Uranus moves in an almost perfectly circular orbit, therefore maintaining a constant distance from the Sun.
B.
not present at any point on the planet, because dense clouds shield it from climate changes.
C.
nonexistent, because such variations at any point on the planet would be smoothed out during its long “year” by the planet's rapid rotation.
D.
extreme, because its spin axis is nearly in its orbital plane.


315.
The orbits of asteroids have a surprisingly large variety of semimajor axes, eccentricities, and inclinations to the ecliptic compared to most of the major planets. What is believed to be the cause of this?
A.
Asteroids are “small” objects, and they formed with the kinds of orbits they now have.
B.
The orbits were stirred up when the Sun passed within the Oort cloud of another star.
C.
Jupiter's gravitational pull has stirred up the asteroid orbits.
D.
One or more Mars-sized planets formed in the asteroid belt, and their gravitational influence stirred up the orbits of the rest of the asteroids.


316.
How was the Cassini division created in Saturn's rings?
A.
A small moon orbited within the division, clearing particles from the gap.
B.
One of Saturn's satellites exerted a resonant pull on particles in the division, clearing a gap.
C.
An intense region of high-energy electrons in Saturn's magnetosphere at that distance eroded the particles from the gap.
D.
The rings simply formed that way in the ancient past.


317.
Which of the following general statements about the Moon is true?
A.
There is one side of the Moon from which Earth can never be seen.
B.
The Moon does not rotate on its axis.
C.
There is one side of the Moon from which the Sun can never be seen.
D.
One side of the Moon is always in darkness.


318.
The most definitive evidence for water ice on Jupiter's satellites has come from
A.
analysis of the albedos of these satellites.
B.
spectroscopic observations.
C.
photographic images of the surfaces from the galileo flyby mission.
D.
temperature analysis of conditions on the surfaces.


319.
Looking at the geologies of the four large Galilean satellites of Jupiter, we find
A.
remarkable uniformity.
B.
totally random characteristics, suggesting that these three moons were formed at various locations far distant from Jupiter and later captured by Jupiter's gravity.
C.
characteristics which change in an orderly fashion with the satellites' distances from Jupiter.
D.
two unique sets of characteristics: Io and Callisto being very similar to each other and Europa and Ganymede being similar to each other, but different from Io and Callisto.


320.
What conditions are considered necessary for a planet to be able to generate an intense magnetic field?
A.
ionized and electrically conducting layer in its atmosphere
B.
solid iron core into which a magnetic field was induced early in the planet's history
C.
electrically conducting material in its interior and slow rotation, because rapid rotation will destroy a magnetic field
D.
relatively rapid rotation and electrically conducting material in its interior


321.
Most lunar craters by far were caused by
A.
lunar quakes, under gravitational tidal disturbance from Earth.
B.
bombardment from space by meteoritic material.
C.
the explosion of rocks caused by thermal shock from alternating intense sunlight and the cold of space.
D.
volcanic eruptions from within the Moon's interior.


322.
Maria are
A.
bright streaks radiating away from young, fresh craters.
B.
isolated regions of heavily cratered highland terrain.
C.
long, sinuous valleys formed by ancient lava rivers.
D.
ancient lava floodplains.


323.
The nearest star beyond the Sun is Proxima Centauri, which is approximately 4.22 light years away. Suppose Proxima Centauri is surrounded by an Oort cloud the same size as our own. What would be the distance between these Oort clouds as a fraction of the distance between these two stars?
A.
0.27
B.
0.63
C.
0.87
D.
0.99


324.
The dark markings near the equator of Mars show seasonal variations because of
A.
changes in coverage of rocks by CO2 ice as the temperature varies from above to below the freezing point of CO2.
B.
changes in the growth of vegetation.
C.
changes in the flow of water released from permafrost by sunlight.
D.
variations in the dust coverage of the surface.


325.
Titan is Saturn's largest satellite. It is unusual among all the planetary moons because of its
A.
strong magnetic field.
B.
location.
C.
dense atmosphere.
D.
rings.


326.
The composition of the clouds that we see on Jupiter is
A.
very different from Earth clouds—composed almost entirely of ammonia and ammonium hydrosulfide crystals with almost no water.
B.
similar to Earth clouds through the whole atmosphere—water droplets and crystals of frozen water.
C.
similar to Earth clouds (water droplets and crystals of frozen water) in the higher levels but very different (e.g., ammonia crystals) in the lower levels.
D.
similar to those of Earth (water droplets and crystals of frozen water) in the lower levels but very different (e.g., ammonia crystals and other chemicals) in the higher levels.


327.
What are zonal winds on Jupiter?
A.
winds blowing horizontally northward and southward above the cloud layer
B.
winds blowing vertically upward and downward in regions of strong convection
C.
winds blowing horizontally in a circular pattern, such as around the Great Red Spot
D.
winds blowing horizontally eastward and westward in the cloud layer


328.
Venus has
A.
no magnetic field.
B.
a very powerful magnetic field.
C.
a magnetic field about the strength of that of Earth.
D.
a weak magnetic field about 1/100 the strength of Earth's magnetic field.


329.
Why would you expect to see no craters, such as those on the Moon or Mars, on Io, the innermost Galilean moon of Jupiter?
A.
because the surface is always reentering the planet's interior by subduction in rapid plate tectonic motion, similar to but faster than that on Earth
B.
because continuous rainfall quickly erodes and washes away all trace of craters
C.
because its liquid surface cannot maintain a crater, just as Earth's oceans cannot do
D.
because volcanoes are continuously depositing new material on the surface


330.
The material in the interiors of Jupiter and Saturn thought to be responsible for their powerful magnetic fields is
A.
molten iron and nickel.
B.
liquid metallic hydrogen.
C.
gases of NH3 (ammonia), CH4 (methane), H2O (water vapor).
D.
solid magnetic iron.


331.
How many large, spherical moons are in orbit around Jupiter?
A.
none
B.
16
C.
11
D.
4


332.
Asteroids whose elliptical orbits have perihelion distances shorter than the orbital distance of Mars are known as
A.
Kirkwood objects, or KOs.
B.
near-Earth objects, or NEOs.
C.
Hirayama family asteroids, or HFAs.
D.
Mars-crossing asteroids, or MCAs.


333.
What is the Cassini division?
A.
the layer of relatively clear air separating Saturn's upper cloud deck from the middle cloud deck.
B.
the boundary between the bright B ring and the faint C ring in Saturn's rings.
C.
a wide, dark gap in Saturn's rings.
D.
a major gap in the asteroid belt.


334.
Compared to that of Earth, the mass of Jupiter is
A.
several thousand times larger.
B.
about 11 times as large.
C.
about 300 times larger.
D.
about 1/300, because of Jupiter's low density.


335.
The lifetime of the Great Red Spot appears to be
A.
similar to that of a sunspot that it resembles—about 2 to 4 weeks between successive appearances.
B.
one Jupiter orbital period—about 12 years between successive appearances, because the spot is produced by tidal effects from interaction with other planets.
C.
at least 300 years, from visual records.
D.
well over 2000 years, from ancient Greek records.


336.
Mercury's magnetic field, compared with that of Earth, is
A.
of equivalent strength.
B.
weak, but strong enough to deflect the solar wind.
C.
extremely weak, so it cannot prevent the solar wind from hitting the surface of Mercury.
D.
much more powerful.


337.
Which of the following early telescope observations convinced Galileo that the Copernican heliocentric model provided a better explanation for the Solar System than did the Greek geocentric model?
A.
sunspots on the Sun and apparent solar rotation
B.
the Moon changing in angular size as it orbits Earth
C.
Venus changing in angular size and apparent shape with time
D.
Moons seen to be orbiting another planet, Jupiter, rather than Earth


338.
The internal structure of Mercury is a
A.
rocky core, a hydrogen-helium atmosphere, and liquid metallic hydrogen in between.
B.
thick, rocky mantle taking up most of the volume of the planet, overlying a small but dense iron core.
C.
dense iron core taking up almost half of the volume of the planet and a rocky mantle surrounding the core.
D.
rocky core with a liquid (or perhaps frozen) water mantle and icy surface.


339.
Which of the following are NOT seen on Jupiter's satellite Io?
A.
sulfur dioxide frost
B.
volcanic plumes
C.
lava flows
D.
impact craters


340.
The greenhouse effect, which heats a planet's surface above the predicted equilibrium surface temperature for the planet without an atmosphere, is far less effective on Mars than on Earth. Why is this?
A.
The Martian surface temperature is very low, and this reduces the effectiveness of the greenhouse effect.
B.
There is less energy being conducted upward from the Martian interior to the surface of Mars because of the thickness of its crust compared to that of Earth.
C.
The Martian atmosphere contains no gases that can absorb solar radiation.
D.
The Martian atmosphere is very thin and traps less infrared radiation from the surface.


341.
Recent calculations show that the Tunguska explosion in Siberia in 1908, which had an explosive power of several hundred kilotons of TNT, was probably caused by
A.
a small comet nucleus about 150 m across suddenly vaporizing in the atmosphere.
B.
the impact and annihilation of a very small amount of antimatter from somewhere else in the universe.
C.
a small natural nuclear explosion in uranium deposits.
D.
a small stony asteroid about 80 m across disintegrating explosively in the atmosphere before hitting the ground.


342.
What is the most likely cause of the smooth and relatively crater-free surfaces of lunar maria?
A.
volcanic ash that rained on the surfaces of the basins in recent geological times
B.
dust storms that eroded and smoothed the surface
C.
sediments left behind after water flowed into the basins and evaporated
D.
lava flows relatively late in the geological history of the Moon


343.
What is the mass of Saturn compared to the mass of Jupiter?
A.
about 1.5 times the mass of Jupiter
B.
about 1/10 the mass of Jupiter
C.
about 1/3 the mass of Jupiter
D.
almost the same mass


344.
Which of the following has apparently had the least influence on the evolution of the surface and geology of Mars?
A.
water flow
B.
an internal magnetic field
C.
erosion by winds
D.
impacts by meteoroids


345.
Why does no major planet orbit the Sun at the location of the asteroid belt?
A.
In the early solar nebula, the temperature that close to the Sun was too high for rock or iron to condense into solid form.
B.
One such object did form there but was destroyed by a collision with an early comet; the asteroid belt is the debris from the collision.
C.
Jupiter's gravitational pull stirred up the planetesimals, preventing them from coalescing into a single large object.
D.
Three Earth-sized planets did form there, but they destroyed each other by mutual collisions; the asteroid belt is the debris from these collisions.


346.
Which of the following chemicals is the least abundant in the atmosphere of Jupiter?
A.
NH3—ammonia
B.
H2O—water vapor
C.
CH4—methane
D.
CO2—carbon dioxide


347.
How many of the large Galilean satellites are in synchronous rotation around Jupiter (always turning the same face toward Jupiter)?
A.
all 4
B.
only Io
C.
the inner 3
D.
the inner 2


348.
A major feature of the atmosphere of Mars is
A.
occasional strong winds and dust storms.
B.
very dense clouds shrouding most of the planet.
C.
a chemical mixture very similar to that of Earth.
D.
very high temperatures and pressures.


349.
The structure of Callisto, the outer Galilean satellite of Jupiter, is thought to be
A.
a thick ice crust and a slushy mantle of ice and water over a core of rock.
B.
mostly or entirely rock with no firm evidence of an iron core, and active volcanoes on its surface.
C.
a large rocky core with a thin layer (100 km thick) of ice and water over it.
D.
a jumbled mixture of about half rock and half ice.


350.
The fact that there are several distinct and different types of meteorites (stony, stony-iron, and iron) is probably indicative of
A.
preferential accretion of iron particles to other iron particles because of their magnetic properties, leaving stony particles to accrete separately.
B.
fragmentation of asteroids that had become differentiated in a similar fashion to Earth (with the heavier iron sinking to the center).
C.
different amounts of heating and “erosion” of the outer layers of meteorites as they pass through Earth's atmosphere.
D.
formation in different parts of the early solar nebula, with stones condensing closer to the Sun and irons farther out.


351.
The oblateness of Jupiter, which is a measure of the amount by which its equatorial diameter exceeds its polar diameter and is a consequence of its fluid structure and rapid rotation, is
A.
zero, or perfectly spherical, because the planet is fluid.
B.
6.5%.
C.
10%.
D.
32%.


352.
Showers of shooting stars or meteors are seen at regular times each year on Earth because
A.
Earth passes through the fringes of the asteroid belt at these times.
B.
Earth is bombarded by material, including dust grains, ejected from the Sun during regular sunspot activity.
C.
Earth runs into material within the spiral arm structure of the Milky Way at these times.
D.
Earth passes through a cloud of remnant dust and rock fragments from an old comet that is circling the Sun in the comet's old orbit.


353.
It has been known that Jupiter has moons since
A.
the time of the ancient Greeks.
B.
the Voyager flybys in 1979.
C.
Galileo turned his telescope to the sky in 1610.
D.
Isaac Newton predicted their existence in 1708.


354.
The name 1987 FD refers to the
A.
fourth asteroid to be discovered in the month of February, 1987.
B.
sixth asteroid to be discovered in the month of April, 1987.
C.
1987th asteroid ever to be discovered, named after Frances Draibre.
D.
fourth asteroid to be discovered during the second half of March, 1987.


355.
The moons of Uranus orbit the planet
A.
in a plane inclined a few degrees to the ecliptic, like the Jovian moons.
B.
in the plane of the ecliptic.
C.
in polar orbits (orbits over both poles).
D.
in the same plane as the rings.


356.
There is no evidence of plate tectonics (continental drift) on Mercury. The most likely explanation is that
A.
the planet cooled too slowly and the mantle remained too soft.
B.
the planet cooled too rapidly and the mantle became too rigid.
C.
Mercury has no iron core like Earth.
D.
plate tectonics can only occur on a body with continents separated by oceans.


357.
The surface temperature of Venus has been found by radio observations and by remote exploration by American and Soviet spacecraft to be approximately
A.
190 K.
B.
273 K.
C.
460 K.
D.
730 K.


358.
The Tharsis rise on Mars, a region that is higher than the surrounding plain by about 5 km (over 16,000 ft), was caused by
A.
the collision of two tectonic plates.
B.
the focusing of seismic waves from the impact of a massive asteroid at the diametrically opposite point on Mars.
C.
an upwelling magma plume in Mars's interior, which has raised this whole region.
D.
erosion of the surrounding plain by massive floods.


359.
What characteristic of Jupiter's moon Io makes it different from any other known satellite in the Solar System?
A.
It has geyser-like plumes of nitrogen gas.
B.
It is volcanically active.
C.
It has a permanent, dense atmosphere which totally obscures the solid surface.
D.
Its surface shows uncratered, flooded regions (now frozen) and other signs of geologically recent activity involving water.


360.
Maria on the Moon exist
A.
uniformly all over the surface of the Moon.
B.
only in a zone around the equator.
C.
only in the north and south polar regions.
D.
only on Earth-facing side of the Moon.


361.
How did the discovery of Neptune differ from the discoveries of Uranus and Pluto?
A.
Neptune's presence was first predicted using Newton's gravitational law to interpret deviations in the motion of another planet, whereas Uranus and Pluto were discovered during sky searches.
B.
Neptune was discovered by accident by an amateur astronomer, whereas Uranus and Pluto were both found by professional astronomers doing specific searches for a new planet.
C.
Neptune was found during a survey of the sky, whereas Uranus and Pluto were found after being predicted on the basis of their gravitational influence on the motions of neighboring planets, Saturn and Neptune, respectively.
D.
Neptune was discovered by photographic surveys of the sky, whereas Uranus and Pluto were found by visual searches.


362.
Compared to the surface of Earth, that of Venus is
A.
extremely rugged, with deep valleys and many high volcanic mountains.
B.
completely covered with innumerable, overlapping craters and old crater walls that constitute mountain ranges.
C.
very smooth and flat, with no mountains or structure.
D.
almost completely flat and relatively smooth, apart from two high volcanic mountain ranges.


363.
Jupiter's Great Red Spot is probably
A.
a continent.
B.
a storm.
C.
an optical illusion.
D.
a hole in the clouds.


364.
The major constituent of Saturn is
A.
rock.
B.
carbon dioxide.
C.
hydrogen.
D.
nitrogen.


365.
An astronomer detects a new feature in Jupiter's atmosphere. Subsequent observation shows that this feature is brighter than its surroundings when observed in infrared light. We can conclude that this feature is a
A.
localized storm feature.
B.
region of higher density in the ammonium hydrosulfide layer.
C.
region of high-altitude clouds created by upwardly moving winds.
D.
deeper layer observed through a hole in Jupiter's clouds.


366.
The central core of Mercury is probably composed of
A.
molten rock.
B.
solid rocks of relatively low density.
C.
ices of H2O and CH4.
D.
solid and/or molten iron.


367.
A chunk of rock and metal 10 km in diameter orbiting the Sun would be called
A.
an asteroid.
B.
a meteoroid.
C.
a moon.
D.
a comet.


368.
The overall interior structure of Jupiter and Saturn is expected to be
A.
three-layered—a large, solid, inner core of rock, a liquid outer core of “ices,” and an extensive gaseous, hydrogen-rich atmosphere.
B.
four-layered—a solid iron inner core, a liquid iron outer core, a partially molten mantle of rock, and a solid crust.
C.
a ball of hydrogen and helium of gradually increasing density inward from gas to liquid to solid.
D.
four-layered—a rocky inner core, a liquid outer core of “ices,” a mantle of liquid hydrogen and helium, and an extensive gaseous atmosphere.


369.
We have seen that our best Earth-bound views of Mercury and Venus occur when these planets are at their greatest elongations. Where is Mars when we have our best Earth-bound view of it?
A.
greatest western elongation
B.
greatest eastern longation
C.
conjunction
D.
opposition


370.
Which of the following statements is NOT true of the Moon?
A.
It shows no evidence of ever having liquid water on its surface.
B.
Parts of its surface are completely saturated with craters (i.e., no uncratered surface left in these regions).
C.
It has extensive lava floodplains over most of its surface, near side and far side.
D.
It has large basins that were carved out by asteroid impacts.


371.
Craters on Mercury appear to have been produced by
A.
impacts by objects from space continuously throughout the planet's history, including very recently in geological time.
B.
volcanic eruptions early in the planet's history.
C.
successive expansion and contraction of the planet's surface, caused by intense heating by the Sun and severe cooling during rotation, because the craters appear to be in irregular lines across the surface.
D.
impacts from objects early in the planet's history.


372.
The most ambitious mission so far to study the asteroids is
A.
a flyby mission to take close-up images of an asteroid.
B.
a spacecraft which went into orbit around an asteroid.
C.
a soft unmanned landing to gather materials and return them to Earth.
D.
a manned landing to explore the asteroid and then return to Earth.


373.
The spacecraft Clementine observed the Moon in 1994 and provided evidence for ice near the South Pole. How was this information gathered?
A.
A soft landing was made near an ice field.
B.
Radar waves were sent out and their reflection from the lunar surface was detected.
C.
Reflections of ultraviolet, visible, and infrared from the lunar surface were analyzed.
D.
Sensitive heat detectors monitored the lunar surface temperature.


374.
The eruptive plumes observed on Io are thought to most closely resemble
A.
terrestrial midocean ridges, where upwelling molten rock pushes the crust apart.
B.
geysers, where material is shot upward by the pressure of gas produced below the surface.
C.
volcanoes, producing lava flows and columns of erupting silicate ash.
D.
explosions, where material is thrown upward by a single burst and then falls back to the surface.


375.
Which of the following objects in the solar system rotates quickest around its own axis?
A.
Earth
B.
the Sun
C.
Jupiter
D.
Earth's moon


376.
Each of the following statements about the similarities of Mercury and our Moon is true, except one. Which comparison is not valid?
A.
Both have very dark surfaces and low reflectivities or albedos.
B.
Neither has an atmosphere.
C.
Both have heavily cratered surfaces.
D.
Both have large, circular, and relatively flat basins or maria on parts of their surfaces.


377.
Compared to earthquakes, moonquakes are
A.
much more frequent but significantly weaker, occurring at any time.
B.
much less frequent but significantly stronger, occurring mostly at full moon.
C.
much weaker and less frequent, occurring mostly when the Moon is at perigee.
D.
nonexistent, the Moon being seismically quiet.


378.
Computer simulations of the formation of the Solar System show that the material in the vicinity of the asteroid belt did not form into a much larger planet because
A.
of a violent collision between two protoplanets, the debris from which became the asteroid belt.
B.
Jupiter's gravitational pull flung most of the material in this region out of the Solar System and prevented coalescence of the rest.
C.
this region is where the gravitational field of the Sun is often balanced by that of Jupiter, and this prevented coalescence of matter into a planet.
D.
this material was inside the Roche limit for the gravitational field of Jupiter.


379.
The high-speed winds observed on Jupiter occur mainly
A.
in a north-south direction from the dark belts toward the light zones.
B.
near the centers of the dark belts.
C.
at the boundaries between the dark belts and the light zones.
D.
near the centers of the light zones.


380.
If astronauts set up a permanent settlement at Tranquility Base on the Moon, how many times each year would the Sun rise and set as seen by a resident of this base?
A.
365 times each year
B.
once each year
C.
never—the Sun would remain motionless in the sky
D.
about once per month


381.
The general shape of most asteroids is thought to be
A.
double, two asteroids orbiting the Sun together.
B.
perfectly spherical.
C.
loose collections of very small particles, held together by gravity.
D.
irregular.


382.
The outer three Galilean moons of Jupiter differ from Io, the innermost such moon, by having surfaces of
A.
water ice.
B.
smoothly polished rock.
C.
carbon dioxide.
D.
sulfur.


383.
What appears to be the “impact history” of cratering on the Moon?
A.
more or less constant bombardment from the earliest times to the present
B.
heaviest bombardment when the Moon first formed, gradually decreasing (except for increased activity about four billion years ago) to light bombardment today
C.
short periods of heavy bombardment alternating with long periods of light bombardment throughout the Moon's life
D.
an early period of heavy bombardment followed by a decrease in intensity (except for a spike around four billion years ago) and then very light bombardment to the present


384.
Perhaps the most interesting material to be found inside rocks that have come to us from outer space is
A.
radioactive material.
B.
amino acids or proteins.
C.
carbon.
D.
pure iron.


385.
The orbits of comets are
A.
randomly oriented in the Solar System and can extend far beyond the orbit of Pluto.
B.
randomly oriented in the Solar System and confined to distances closer to the Sun than approximately the orbit of Pluto.
C.
primarily in the plane of the ecliptic and confined to distances closer to the Sun than approximately the orbit of Pluto.
D.
primarily in the plane of the ecliptic and can extend far out beyond the orbit of Pluto.


386.
Neptune's predominantly blue appearance is caused by
A.
the fact that solar light has lost much of its red light by scattering in the interplanetary medium by the time it reaches Neptune.
B.
auroral emissions caused by solar wind particles exciting the atoms and molecules in Neptune's high atmosphere.
C.
preferential scattering of the blue end of the solar spectrum by Neptune's atmosphere, similar to the process that causes the blue sky on Earth.
D.
the absorption of reflected sunlight at the red end of the spectrum by methane in its atmosphere.


387.
Ganymede, one of the large Galilean satellites of Jupiter, is very different from the Earth, but in which one of the following ways does Ganymede RESEMBLE Earth?
A.
Like Earth, but unlike all other moons in the Solar System, Ganymede has a dense atmosphere.
B.
Based on its density, Ganymede appears to have a large iron core surrounded by a thick rocky mantle directly beneath its icy crust.
C.
Ganymede has active volcanoes.
D.
Ganymede appears to have had tectonic activity at some time in its past.


388.
Which one of the following parts of a comet is not visible to the naked eye?
A.
dust tail
B.
ion tail
C.
coma
D.
hydrogen envelope


389.
A shield volcano is a
A.
volcanic dome on the side of a larger volcano that shields the surrounding plains from inundation by lava from the main vent.
B.
very broad volcano with gently sloping sides, similar in shape to an ancient Greek shield.
C.
tall volcano with steep sides, similar in shape to the central ornament of an ancient Roman shield.
D.
vast lava flood-plain originating from a ground-level fissure, similar in size and topography to the Canadian Shield rock formation.


390.
Jupiter's strong magnetic field
A.
has no effect on Io.
B.
is the main cause of the geologic activity on Io.
C.
contains many charged particles which have been ejected from Io.
D.
has caused Io to go around Jupiter in a synchronous orbit.


391.
Neptune's high cirrus clouds consist of
A.
crystals of water ice.
B.
droplets of sulfuric acid.
C.
ammonia ice crystals.
D.
methane ice crystals.


392.
The Oort cloud is
A.
a band of dust in the plane of the ecliptic, extending from the orbit of Mars to beyond the orbit of Pluto.
B.
an approximate spherical distribution of comets centered on the Sun, extending out to about 50,000 AU.
C.
another name for the early solar nebula.
D.
a relatively flat distribution of comets in the plane of the ecliptic, extending from around the orbit of Pluto out to about 500 AU from the Sun.


393.
Which of the following motions is seen to be characteristic of the four Galilean moons of Jupiter?
A.
They orbit the planet in a planar orbit carrying them over both the north and south poles of Jupiter.
B.
They orbit the planet in the opposite direction to the planet's rotation.
C.
They each keep the same face toward the Sun at all times.
D.
They each keep the same face toward the planet at all times.


394.
A meteor shower occurs when
A.
Earth passes through the asteroid belt.
B.
the head of a comet hits Earth's atmosphere.
C.
a meteor is about to get married.
D.
Earth passes through a swarm of dust particles in space.


395.
One example of a near-Earth object, or NEO, is the
A.
asteroid Eros.
B.
Moon.
C.
asteroid Ceres.
D.
Trojan asteroid Hector.


396.
What is the approximate orbital period of an object that is moving in a circular orbit around the Sun in the Oort cloud?
A.
1000 years
B.
100,000 years
C.
10,000 years
D.
10 million years


397.
Comet tails are the result of
A.
sunlight glinting on and reflecting from the icy nucleus of the comet.
B.
dust collected by the comet as it moves in its orbit.
C.
solar wind particles being guided and excited to emit light by the comet's magnetic field.
D.
melting and evaporation of ices from the comet's nucleus.


398.
Mercury is much closer than Venus to the Sun, and yet it never appears brighter than Venus, even when both are at maximum brightness, because
A.
Mercury is larger than Venus, but it has a thick atmosphere which impedes reflection from its surface, making it appear dark.
B.
we never see more of Mercury than a thin crescent because of its orbital path relative to that of Earth.
C.
Mercury has average reflectivity but is very small and hence appears relatively dark.
D.
Mercury is small, has a dark surface, and has no reflecting clouds.


399.
The outer cores of Jupiter and Saturn are made of “ices,” which are actually in the liquid state. Why are they not solid?
A.
The pressure here is too great.
B.
The temperature here is too high.
C.
These ices consist of hydrogen and helium, which cannot exist in a solid form.
D.
The constant agitation caused by the planets' rotation prevents the formation of a solid.


400.
The four major moons of Jupiter are collectively named after which early astronomer?
A.
Copernicus
B.
Newton
C.
Ptolemy
D.
Galileo


401.
It is believed there were originally far more objects in the asteroid belt than there are now. What happened to the rest of them?
A.
The gravitational influence of Jupiter deflected most of them out of the Solar System.
B.
Mars-sized objects moving through the asteroid belt disrupted the orbits and deflected most of them out of the Solar System.
C.
The majority of the original asteroids coalesced to form a series of Mars-sized objects, one of which struck Earth and caused the formation of the Moon.
D.
A passing star pulled most of the original asteroids out of the Solar System.


402.
The blue-green appearance of Uranus is caused by
A.
the atmosphere of methane gas, which preferentially absorbs the red parts of the solar spectrum.
B.
the reflection of blue light by the ice crystals on the planet's surface and in its atmosphere.
C.
the color of the surface of the planet.
D.
scattering of light from the dust in the thick atmosphere.


403.
The dominant component of the regolith on Mars is probably
A.
basaltic lava pulverized by meteoritic bombardment.
B.
concrete from ancient canals, pulverized by meteoritic bombardment.
C.
volcanic ash from geologically recent eruptions.
D.
iron-rich clay.


404.
In which of the following planets was a ring system first discovered by the occultation or blocking of light from a distant star, as the planet and rings moved in front of it?
A.
Saturn
B.
Uranus
C.
Mercury
D.
Jupiter


405.
How did the inner planets, Venus and Earth, acquire their original atmospheres?
A.
capture of solar wind gases from the Sun as they stream past the planets
B.
the impact and melting of icy comets and asteroids from the planetary system and perhaps beyond
C.
gravitational capture of material from the original solar nebula by the planets
D.
outgassing of the planets through volcanoes and other vents


406.
What happened to the Mars-sized planets believed to be a part of the asteroid belt early in the Solar System's history? Three of these answers are reasonable fates for these planets and one is not. Which one is not a reasonable final scenario for these planets?
A.
Gravitational interaction with Jupiter eventually kicked them out of the Solar System.
B.
Gravitational interaction with Jupiter caused them to fall into the Sun.
C.
They collided with other large bodies and shattered.
D.
They are still present in the asteroid belt, although not yet detected.


407.
The ring system around Uranus was originally discovered by what observation technique?
A.
infrared observations from the IRAS spacecraft in Earth's orbit
B.
occultation of light from a star as Uranus (and the rings) passed in front of it
C.
radar reflection from the particles in the rings
D.
observation by the cameras on board the Voyager 1 spacecraft


408.
Which one of the following bodies has an orbit with the greatest inclination to the orbit of Earth, i.e., to the ecliptic?
A.
Neptune
B.
Mars
C.
Mercury
D.
Pluto


409.
The composition of Jupiter's clouds is
A.
liquid droplets of water and ammonia.
B.
ice crystals of water, ammonium hydrosulfide, and carbon dioxide.
C.
water-ice crystals.
D.
ice crystals of ammonia, ammonium hydrosulfide, and water.


410.
The Moon's appearance, when its whole surface is examined, could be described as
A.
craters only on the near side, smooth surface on the far side.
B.
surface features uniformly distributed.
C.
many maria distributed uniformly on both the near and far sides.
D.
maria only on the near side, no major maria on the far side.


411.
The rings of Saturn are in which plane with respect to the planetary system?
A.
a plane inclined at an angle to both the orbital and equatorial planes of the planet, and to the ecliptic plane, which is why we can easily see the rings face-on from Earth
B.
the orbital plane of Saturn around the Sun
C.
the equatorial plane of Saturn
D.
the ecliptic plane


412.
The tilt of Uranus's axis was first deduced from observed orbital motions of its moons. For the deduction of this tilt to be correct, it was necessary to assume that
A.
the moons moved in the ecliptic plane, or at least in the plane of the orbit of Uranus.
B.
the moons passed over both north and south poles of the planet, thereby indicating the planet's spin axis.
C.
the moons were not affected by the gravitational field of the Sun, which would force their orbits to deviate from the planet's equatorial plane.
D.
the moons were orbiting in the equatorial plane of Uranus.


413.
What property is shared by the Earth and Europa, one of Jupiter's large moons?
A.
They have both been shown to harbor intelligent life in their oceans.
B.
They both have thick atmospheres of nitrogen and oxygen.
C.
Both have warm oceans of water.
D.
They are about the same physical size.


414.
Venus appears to be very bright in our skies at certain times because
A.
even though its surface is very dark, it is relatively close to the Sun.
B.
it is glowing from the heat of its surface, where the temperature is 750 K.
C.
its rocky surface is shiny, like the surface of new volcanic lava.
D.
it is relatively close to the Sun, Earth is close to it, and it is covered by very reflective clouds.


415.
The rotation rate of the planet Venus was first determined by measuring
A.
the time delay of radio pulses after reflection from the planet's surface.
B.
the Doppler shift in radio waves reflected from the planet's surface.
C.
photography from the Hubble Space Telescope at infrared wavelengths that penetrate the planet's clouds.
D.
sequential photography of Venus from Earth.


416.
Who was the first person to report seeing the rings of Saturn although he did not realize that they were rings?
A.
We do not know—the rings have been known since ancient times.
B.
Galileo Galilei
C.
Christiaan Huygens
D.
Johannes Kepler


417.
Where in the solar system would you look for liquid hydrogen?
A.
nowhere, because it is not cold enough anywhere in the solar system to liquefy hydrogen.
B.
at the polar regions of the Moon.
C.
in the deep interiors of Jupiter and Saturn.
D.
on the polar caps of Mars.


418.
Over time, what fraction of the Moon's surface can we see from Earth?
A.
about 60%, because of the shape and orientation of the Moon's orbit and rotation axis
B.
52%, because two observers on Earth see the Moon from slightly different angles
C.
100%, because of the rotation of the Moon about its axis
D.
exactly 50%, because the Moon is in synchronous rotation around Earth


419.
On what planet would you not expect to find an aurora?
A.
Venus
B.
Earth
C.
Jupiter
D.
Saturn


420.
Most of the asteroids of our Solar System move around the Sun between the orbits of the planets
A.
Earth and Mars.
B.
Mars and Jupiter.
C.
Jupiter and Saturn.
D.
Venus and Earth.


421.
Neptune was discovered by
A.
the careful application of Newton's laws to the motion of other planets.
B.
an astronomer who was conducting a sky survey.
C.
a more precise theoretical prediction.
D.
a careful search by an astronomer in the 1930s who was convinced that one extra planet must be out there.


422.
The dust tail of a comet has which of the following characteristics?
A.
curved, wide, without structure, and transparent to starlight
B.
spherical, very large, and of low brightness, centered on the comet nucleus, showing up on only UV photographs
C.
narrow, straight, and pointed directly at the Sun at all times
D.
long, straight, structured, and pointed directly away from the Sun


423.
Jupiter has a magnetic field that is
A.
much stronger than that of Earth and greatly extended in space.
B.
about the same strength and extent as that of Earth.
C.
variable, often nonexistent, sometimes existing only at the Great Red Spot, which behaves like a sunspot.
D.
very strong and localized close to the planet.


424.
Iron meteorites
A.
are normally composed almost entirely of iron and nickel.
B.
are normally composed almost entirely of iron.
C.
normally contain between three and five times as much iron as terrestrial rocks, in the form of pure grains embedded a rocky matrix.
D.
are normally composed almost entirely of iron, nickel, and carbon.


425.
One distinctive feature that is visible on the “surface” of Jupiter through a telescope from Earth is
A.
the Cassini Division.
B.
Maxwell Montes.
C.
Olympus Mons.
D.
the Great Red Spot.


426.
Widmanstätten patterns are a test for which kind of meteorite?
A.
stones
B.
stony irons
C.
irons
D.
carbonaceous chondrites


427.
The impact of a 10-km-diameter asteroid on the surface of Earth would very likely
A.
shatter Earth into fragments.
B.
create havoc near the impact site but have relatively little lasting effect elsewhere.
C.
shatter the global ecology and cause the extinction of a large percentage of all species living on Earth.
D.
completely destroy all life on Earth.


428.
Because of the tides on Earth's oceans, the Moon is
A.
shrinking.
B.
unaffected and continues to orbit in a constant elliptical path.
C.
moving slowly toward Earth.
D.
spiraling outward away from Earth.


429.
The luminous trails of small dust particles that are completely vaporized in Earth's atmosphere and are commonly known as shooting stars are
A.
meteoroids.
B.
meteors.
C.
auroral flashes.
D.
meteorites.


430.
Tectonic activity on Venus differs from that on Earth in that
A.
active crustal deformation appears to be completely absent.
B.
the lithosphere appears to be softer or more plastic and cannot support the creation and motion of solid plates (flake tectonics).
C.
the lithosphere appears to be cooler and thicker and is therefore too rigid to break up into moving plates.
D.
mantle convection appears to be more vigorous and has broken the lithosphere into a multitude of small plates instead of a few large ones.


431.
Triton, the largest satellite of Neptune, has
A.
a surface of ice with frozen lakes, plumes of escaping gas, and few craters.
B.
a densely cratered surface of ice, with at least one ringed structure indicating an ancient asteroid impact.
C.
a surface of ice in which ancient, densely cratered regions are surrounded by interconnecting systems of parallel ridges.
D.
a thick atmosphere that hides the surface from view.


432.
The maria on the Moon appear to be
A.
former ocean basins from which the water has escaped.
B.
lava flows around giant ancient volcanoes.
C.
craters filled with basalt from within the Moon.
D.
evenly distributed on the near side and the far side of the Moon.


433.
How are space probes to the outer planets, such as Jupiter, protected from being obliterated by collisions with asteroids in the asteroid belt?
A.
They aren't—we lose only one out of every four spacecraft to collisions with asteroids, so it is cheaper to take our chances.
B.
The spacecraft are equipped with cameras to detect asteroids, so they can be directed safely around them.
C.
They aren't—asteroids are so far apart that the spacecraft just sail safely on through.
D.
The spacecraft are sent in an inclined orbit that arcs above or below the asteroid belt, crossing the ecliptic again near Jupiter.


434.
Which is the eighth planet from the Sun in order of increasing semimajor axis?
A.
Pluto
B.
Saturn
C.
Uranus
D.
Neptune


435.
The interesting feature of Jupiter's rotation is that
A.
it rotates in a direction opposite to that of most of the planets and opposite to its direction of revolution around the Sun.
B.
its rotation rate has slowed down significantly since it was first observed through telescopes in the 1600s.
C.
regions at different latitudes appear to rotate at different rates.
D.
its axis of rotation lies almost in the plane of its orbit.


436.
Uranus lacks an internal source of heat. One consequence of this is that
A.
Uranus lacks dynamic atmospheric activity.
B.
it is much colder than Neptune, even though it is closer to the Sun.
C.
the atmosphere is very thin because most of the atmospheric materials lie frozen on the surface.
D.
frozen material on the surface results in a much higher albedo than, say, Neptune.


437.
The densities of the four Galilean satellites of Jupiter are
A.
all low, typical of rock and ice, because they formed in the outer Solar System.
B.
very low because, as with Jupiter, they are composed mostly of hydrogen.
C.
high (rocky) for the two inner satellites because they formed close to Jupiter, low (rock and ice) for the two outer satellites because they formed farther away from Jupiter.
D.
all high, typical of rock, because they are planetary satellites (similar to our Moon).


438.
The object whose discovery was prefaced by accurate prediction using the measured deviations of known planets from regular orbits and the application of Newton's laws of mechanics, is
A.
Uranus.
B.
Neptune.
C.
Pluto.
D.
Mercury.


439.
The low average density of Jupiter (about 1300 kg/m3 compared with that of water, 1000 kg/m3) indicates that this planet is composed mainly of
A.
hydrogen, in liquid or gaseous form.
B.
helium as gas and liquid only, because low temperatures and great pressures are needed to form solid helium.
C.
water, compressed somewhat by gravity, maybe in the form of ice.
D.
methane, ammonia, and water, from spectroscopic observation of its atmosphere.


440.
Which is the most probable heat source that produced extensive and possibly total melting of the Moon at an early stage in its history?
A.
tidal flexing and distortion caused by its motion around Earth
B.
decay of radioactive elements within it and the impact energy of meteoritic bombardment
C.
intense sunlight from the early and very active Sun
D.
nuclear fusion reactions occurring in its core


441.
Why do most comets have very elliptical orbits, often extending far out beyond the orbit of Pluto?
A.
They originally formed in circular orbits far from the Sun (> 500 AU), and passing stars have perturbed them into long, elliptical orbits.
B.
They are interstellar objects that have been captured in orbit by the Sun.
C.
They formed so far from the Sun (e.g., 10,000 AU) that their orbits naturally drop deeply into the inner Solar System.
D.
They originally formed outside the orbit of Pluto and were flung into highly elongated orbits by the giant planets.


442.
The Moon apparently has
A.
a small iron-rich core that was entirely molten in the Moon's history, as shown by magnetic measurements.
B.
an iron core that takes up about half the volume of the Moon, as shown by the very high average density of the Moon.
C.
no dense iron-rich core of any kind, as indicated by gravity measurements using orbiting spacecraft.
D.
a small, molten iron-rich core at the present time, as indicated by the Moon's weak global magnetic field.


443.
In order to measure Venus's rotation it was necessary to send a beam of electromagnetic radiation through the cloud layer. This electromagnetic radiation was
A.
ultraviolet.
B.
visible.
C.
infrared.
D.
radio.


444.
The rotation periods of Jupiter and Saturn are
A.
very short—on the order of 1 hour.
B.
very long—several weeks because of their great size and mass.
C.
long—on the order of several days.
D.
relatively short—on the order of 10 hours.


445.
Many craters on the Moon are characterized by a central peak. What is the significance of this?
A.
This is strong evidence that lunar craters are volcanic in origin.
B.
a central peak is characteristic of an impact crater formed by a shock wave.
C.
The crater has dug into the lunar surface far enough to uncover an ancient mountain range.
D.
The crater was formed by impact, but it has penetrated into the lunar surface far enough to evoke lava flow which has produced a volcanic cone.


446.
One of the major planets has its spin axis lying almost in its orbital plane. Which planet is this?
A.
Saturn
B.
Uranus
C.
Neptune
D.
Mars


447.
The typical size of the coma or gas cloud surrounding the comet nucleus as it reaches its closest point to the Sun is about
A.
108 km.
B.
107 km.
C.
106 km.
D.
10 km.


448.
The dark, seasonal markings on Mars that grow in the spring and fade in the autumn are believed to result from
A.
microbial activity in the soil (or regolith).
B.
lighting effects that vary as the angle of the Sun changes with the seasons.
C.
dust being blown by winds, alternately covering and uncovering dark rocks.
D.
plant life.


449.
What effect does Jupiter have on asteroids in the asteroid belt?
A.
It will disturb only the orbits of those asteroids whose orbital distances (or semimajor axes) are a simple fraction (e.g., 1/2, 1/3, 2/3, 2/7) of the radius of Jupiter's orbit.
B.
It perturbs only the orbits of asteroids whose orbital periods are a simple fraction (e.g., 1/2, 1/3, 2/3, 2/7) of its own orbital period.
C.
It has no effect whatsoever on such small objects because they are a long way away from Jupiter, and Jupiter's gravitational influence varies as the inverse square of distance by Newton's law.
D.
It disturbs only the orbits of all the asteroids in the belt, slowing them down and causing them to spiral slowly toward the Sun.


450.
The most striking characteristic observed on the surface of Iapetus, one of the outer satellites of Saturn, is
A.
a brightness variation, its leading hemisphere being as dark as asphalt whereas its trailing hemisphere appears as bright as ice.
B.
plumes of nitrogen gas rising from cracks in the icy surface, apparently as a result of geyser activity.
C.
a crater so large that the impact that created it must have come close to shattering the satellite.
D.
an interconnecting network of parallel grooves, indicating tectonic activity in geologically recent times.


451.
The so-called maria, or “seas” on the lunar surface, do not and could not contain water because
A.
the water would boil and evaporate away rapidly in the vacuum of space.
B.
any water falling on the porous surface would soak into it.
C.
the water would have frozen into permafrost in the intense cold on the lunar surface.
D.
the water would react chemically with the surface rocks.


452.
The surface and near-surface atmospheric conditions on Venus are
A.
no atmosphere, very variable temperature.
B.
dense methane, ammonia, and H2O atmosphere, low temperature.
C.
CO2 atmosphere, low pressure, and low temperature.
D.
CO2 atmosphere, high pressure, and high temperature.


453.
All of the following exist on Titan except:
A.
clouds.
B.
liquid water on the surface.
C.
rain.
D.
nitrogen in vapor form.


454.
Phobos and Deimos are moons of which planet?
A.
Mercury
B.
Venus
C.
Mars
D.
Jupiter


455.
A small piece of rock orbiting the Sun would be called
A.
a meteor.
B.
a meteorite.
C.
a micrometer.
D.
a meteoroid.


456.
By dating the Moon rocks we can determine its age. How long ago did the Moon form?
A.
The maria are about 3.8 billion years old, suggesting that the entire Moon was molten at that time—so that is its probable age.
B.
The oldest rocks in the lunar highlands are about 4.3 billion years old, so that must be the age of the Moon.
C.
We believe the Moon was formed molten and then cooled. Because the oldest rocks are about 4.3 billion years old, the formation of the Moon must have occurred around 4.5 billion years ago.
D.
Because it cooled and solidified almost to its core, the Moon must be at least a billion years older than Earth. Its age, therefore, must be at least 5.5 billion years.


457.
Mercury's average density and the fact that it has a (weak) magnetic field leads to the conclusion that its central core is probably composed of
A.
solid and/or molten iron.
B.
molten rock.
C.
solid rocks of relatively low density.
D.
ices of H2O and CH4.


458.
Evidence of hot-spot volcanoes caused by hot, rising plumes under the planet's surface is present on Venus and Mars, as well as on Earth. What distinguishes those on Earth from those on the other planets?
A.
Those on the other planets occurred on tectonic plate boundaries and they are therefore distorted and have spread over the planet surface.
B.
Plate tectonics on all three planets has formed chains of small volcano cones but those on Earth have all occurred under the sea and are hidden.
C.
This type of volcano occurred only at the spin axes or poles of the other planets where tidal stress was greatest, whereas on Earth they occurred near the equator.
D.
Plate tectonics on Earth has moved the hot-spot volcanic site continuously over recent geological time, whereas no such movement has occurred on Venus or Mars.


459.
The moons of Mars are
A.
ice-covered; spherical but flattened by rapid rotation.
B.
irregularly shaped, cratered, and grooved.
C.
spherical and smooth-surfaced (no visible craters or volcanoes).
D.
spherical, with active volcanoes.


460.
One effect of the tidal drag of the ocean waters on Earth is to
A.
speed up Earth in its orbital motion around the Sun.
B.
speed up its rate of spin, thereby gaining energy from the Moon's orbital motion.
C.
slow down Earth's spin rate.
D.
tilt its spin axis farther and farther away from the perpendicular to the ecliptic.


461.
The most geologically active object in the planetary system at the present time is
A.
Io, a moon of Jupiter.
B.
the Earth's Moon.
C.
the Earth.
D.
Mars.


462.
A comet's tail is always aligned from the comet head in a direction
A.
away from the Sun.
B.
toward the nearest planet, because of mutual gravitational attraction.
C.
in a direction along its orbital path, always behind the comet.
D.
toward the Sun, because of gravitational attraction.


463.
The magnetic field of Mars, compared to that of Earth, is
A.
nonexistent anywhere on the planet.
B.
very similar in strength and orientation, its north-south axis being almost along the planet's spin axis.
C.
localized and very weak.
D.
much stronger, but with its north-south axis lying in the equatorial plane, the north pole coinciding with the large volcano, Olympus Mons.


464.
The main gravitational effect that organizes the particles in the rings of Saturn into specific orbits is
A.
the complex gravitational tidal effects of the planet and the Sun on the ring particles.
B.
collisions between the major moons of the planets and the ring particles at the same orbital distance, clearing gaps in the rings.
C.
the perturbing effects of neighboring planets, such as Jupiter and Neptune.
D.
the perturbing effects of major and minor moons or satellites whose orbital periods are related to those of the ring particles by simple ratios (e.g., 2:1, 3:2).


465.
A striking characteristic on Triton, the largest satellite of Neptune, is
A.
a crater so large that the impact that created it must have come close to shattering the satellite.
B.
plumes of dark material driven upward from fissures by nitrogen gas, as a result of either solar or internal heating.
C.
a brightness variation, with one hemisphere being as bright as ice and the other hemisphere as dark as asphalt.
D.
an interconnecting network of parallel grooves, indicating tectonic activity in geologically recent times.


466.
The source of excess heat emitted by Jupiter, above that which is absorbed as sunlight and reemitted, is thought to be
A.
heat generated in the interior by the same electrical currents that generate the planet's magnetic field.
B.
heat caused by friction between oppositely directed winds at mid-latitudes.
C.
gravitational potential energy released as heat during its formation stages, still being released.
D.
chemical reactions between methane, ammonia, and water in the planet's atmosphere and clouds.


467.
After the initial formation of the solar system, rocky debris
A.
was essentially absent, having been used up in the formation of the planets.
B.
was quickly vaporized by the heat of the young Sun.
C.
continued to bombard the planets and satellites for almost another billion years.
D.
was quickly swept out of the solar system by the Sun's T-Tauri wind.


468.
Jupiter and Saturn are primarily composed of
A.
gases.
B.
liquids.
C.
solids.
D.
plasma.


469.
Which of Jupiter's satellites is characterized by an exceptionally smooth, icy surface, few craters, and many streaks and cracks?
A.
Ganymede
B.
Callisto
C.
Io
D.
Europa


470.
What characteristic of Saturn's satellite Titan makes it different from any other known satellite in the Solar System?
A.
Its surface is broken into heavily cratered and lightly cratered regions in a pattern similar to plate tectonics.
B.
It has geyser-like plumes of nitrogen gas.
C.
It is volcanically active.
D.
It has a permanent, dense atmosphere.


471.
How well does Ceres fit the Titus-Bode rule?
A.
Neither the Ceres/Mars ratio nor the Jupiter/Ceres ratio falls into the range suggested by the Titus-Bode rule.
B.
The Ceres/Mars ratio fits the Titus-Bode rule but the Jupiter/Ceres ratio does not.
C.
The Ceres/Mars ratio does not fit the Titus-Bode rule but the Jupiter/Ceres ratio does.
D.
Both the Ceres/Mars ratio and the Jupiter/Ceres ratio fall into the range suggested by the Titus-Bode rule.


472.
The particular feature of a comet that exhibits the most structure and always points away from the Sun is
A.
the ion or gas tail.
B.
the coma.
C.
the dust tail.
D.
the hydrogen envelope.


473.
The internal structure of the two largest Jovian planets (from center outward) is
A.
rocky core with an outer layer of liquid “ices,” liquid methane mantle, gaseous methane atmosphere.
B.
iron-nickel core, rocky mantle, solid crust, ocean of liquid “ices.”
C.
rocky core with an outer layer of liquid “ices,” liquid molecular hydrogen layer, liquid metallic hydrogen layer.
D.
rocky core with an outer layer of liquid “ices,” liquid metallic hydrogen layer, liquid molecular hydrogen layer.



STOP This is the end of the test. When you have completed all the questions and reviewed your answers, press the button below to grade the test.