Astronomy

Transits of multiple planet systems can be analyzed to infer planetary masses.

True

As viewed from above Earth's North Pole, all of the planets orbit the Sun in the same (counterclockwise) direction.

True

Astronomers have discovered more planets around other stars than in our Solar System

True

Based on our theory of how our own solar system formed, we would expect that other solar systems would be quite common.

True

Both the existence and the location of Neptune were predicted mathematically before the planet actually was detected by telescope.

True

Earth is the only planet in the solar system known to have plate tectonics.

True

Earth's atmosphere resulted from the impact of icy planetesimals that originated in the outer regions of the Solar System.

True

Higher temperatures make rocks weaker.

True

Hydrogen exists as a gas, liquid, and solid within Jupiter.

True

If Jupiter were 10 times more massive, it would actually have a smaller radius.

True

Jupiter does not have seasons because it has no appreciable axis tilt.

True

Jupiter is slowly shrinking through gravitational contraction today.

True

Mars has virtually no magnetic field.

True

Most of the planets discovered around other stars are more massive than Jupiter.

True

Much of the land on the west coast of North America began as volcanic islands in the Pacific

True

Multiple planets have been identified around other stars via the transit technique.

True

Multiple-planet systems have been identified around other stars via the Doppler technique.

True

Planetary orbits that are face-on to our line of sight produce no Doppler shift in the stellar spectrum.

True

Process of Science: A prediction based on Newton's theory of gravity led to the discovery of Neptune.

True

Some of the moons of the jovian planets have significant atmospheres.

True

Some radioactive isotopes found in meteorites suggest that the solar system may have been formed shortly after a supernova occurred nearby.

True

Spreading centers are marked by mid-ocean ridges where hot mantle material rises upward and then spreads sideways.

True

Synchronous rotation is when a moon's rotation period and orbital period are the same.

True

The more massive planets in the solar system tend to be less dense than the lower mass planets.

True

The process in which one plate slides under another is called subduction and is marked by deep ocean trenches.

True

The signature of a planet is largest in radial velocity measurements when the planet and star are lined up along the line of sight to the telescope.

True

The signature of a planet is largest in transit measurements when the planet and star are lined up along the line of sight to the telescope.

True

The strength of a rock depends on its composition, its temperature, and the surrounding pressure.

True

Very high pressures, like those found deep within planetary interiors, can compress rocks so much that they stay solid even when temperatures are high enough to melt them under ordinary conditions.

True

The total amount of light from a star-planet system drops when the planet goes behind the star

true

Spacecraft have landed on all the terrestrial worlds except A) Mercury. B) Venus. C) Moon. D) Mars.

A

According to modern scientific dating techniques, approximately how old is the solar system? A) 10,000 years B) 4.6 million years C) 4.5 billion years D) 14 billion years

b

The stratosphere is heated by a) warm air rising from the troposphere. b) ultraviolet light from the Sun. c) convection. d) X-rays. e) all of the above

b

What are the main constituents of Earth's atmosphere? a) hydrogen and helium b) nitrogen and oxygen c) oxygen and carbon dioxide d) oxygen and carbon monoxide e) water vapor and oxygen

b

Which of the following correctly states the layers of Earth's atmosphere from closest to the surface to closest to space? a) troposphere, stratosphere, exosphere, thermosphere b) stratosphere, exosphere, thermosphere, troposphere c) troposphere, stratosphere, thermosphere, exosphere d) thermosphere, troposphere, stratosphere, exosphere

c

Infrared radiation emitted by Earth's surface a) heats the troposphere from below. b) causes convection. c) causes weather (storms). d) all of the above e) none of the above

d

Why do we think Mars was once warmer and wetter? a) It has plenty of volcanoes to outgas an atmosphere. b) It doesn't have strong magnetic field to protect from solar wind stripping. c) There is evidence it once had liquid water. It is too cold for that now. d) all of the above e) A and C

d

Within the frost line, planetesimals were composed entirely of rock and outside the frost line planetesimals were composed entirely of ice.

False

In the context of plate tectonics, what is a subduction zone? A) a place where a seafloor plate is sliding under a continental plate B) a place where two plates are slipping sideways against one another C) a place where two plates are pulling apart D) a place where two continental plates are colliding

A

About 2% of our solar nebula consisted of elements besides hydrogen and helium. However, the very first generation of star systems in the universe probably consisted only of hydrogen and helium. Which of the following statements is most likely to have been true about these first-generation star systems? A) There were no comets or asteroids in these first-generation star systems. B) Jovian planets in these first-generation star systems had clouds made of water and other hydrogen compounds. C) These first-generation star systems typically had several terrestrial planets in addition to jovian planets. D) Like the jovian planets in our solar system, the jovian planets in these first-generation systems were orbited by rings.

A

According to our basic scenario of solar system formation, why do the jovian planets have numerous large moons? A) As the growing jovian planets captured gas from the solar nebula, the gas formed swirling disks around them, and moons formed from condensation accretion within these disks. B) Because of their strong gravity, the jovian planets were able to capture numerous asteroids that happened to be passing nearby, and these became the major moons of the jovian planets. C) The large moons of the jovian planets originally formed in the inner solar system and these moons then migrated out to join up with the jovian planets. D) The many moons of the jovian planets remains one of the unexplained mysteries of the formation of our solar system.

A

According to our modern science, which of the following best explains why the vast majority of the mass of our solar system consists of hydrogen and helium gas? A) Hydrogen and helium are the most common elements throughout the universe, because they were the only elements present when the universe was young. B) Hydrogen and helium are produced in stars by nuclear fusion. C) All the other elements escaped from the solar nebula before the Sun and planets formed. D) All the other elements were swept out of the solar system by the solar wind.

A

According to our theory of solar system formation, what three major changes occurred in the solar nebula as it shrank in size? A) It got hotter, its rate of rotation increased, and it flattened into a disk. B) Its mass, temperature, and density all increased. C) It gained energy, it gained angular momentum, and it flattened into a disk. D) Its gas clumped up to form the terrestrial planets, nuclear fusion produced heavy elements to make the jovian planets, and central temperatures rose to more than a trillion Kelvin.

A

According to our theory of solar system formation, which law best explains why the solar nebula spun faster as it shrank in size? A) the law of conservation of angular momentum B) the law of conservation of energy C) the law of universal gravitation D) Einstein's law E = mc2

A

According to present understanding, which of the following statements about the solar wind is not true? A) It is even stronger today than it was when the Sun was young. B) It helped in the transfer of angular momentum from the young Sun to particles that blew into interstellar space, which explains why the Sun rotates so slowly today. C) It swept vast amounts of gas from the solar nebula into interstellar space. D) It consists of charged particles blown off the surface of the Sun.

A

All the following statements about Venus are true. Which one offers evidence of a global repaving about a billion years ago? A) Venus has relatively few impact craters and these craters are distributed fairly evenly over the entire planet. B) Venus has many circular features, called coronae, which appear to be tectonic in origin. C) Venus's largest features are three elevated regions that look somewhat like continents. D) Venus appears to lack any water that could lubricate the flow of rock in its crust and mantle.

A

All the following statements about known extrasolar planets are true. Which one came as a surprise to scientists who expected other solar systems to be like ours? A) Some of the planets orbit their star more closely than Mercury orbits the Sun. B) Most of the planets are quite massive—much more like Jupiter than like Earth. C) Most of the planets orbit stars that are quite nearby compared to the scale of the entire Milky Way Galaxy. D) In some cases, we've found more than one planet orbiting the same star.

A

Assuming that our ideas about how "hot Jupiters" ended up on their current orbits are correct, why didn't our own solar system end up with any hot Jupiters? A) Our solar nebula must have been blown into space shortly after the formation of the jovian planets. B) Our jovian planets must have migrated outward from inside the orbit of Mercury. C) Our solar nebula must have stuck around for an unusually long time after the formation of jovian planets. D) The existence of Earth and the other terrestrial planets prevented the jovian planets from migrating inward.

A

Based on available data, what kind of objects in our solar system do most of the known extrasolar planets resemble? A) jovian planets B) terrestrial planets C) Kuiper belt objects D) None of the above: most extrasolar planets apparently belong to some new category of object.

A

Based on everything you have learned about the formation of our solar system, which of the following statements is probably not true? A) Only a tiny percentage of stars are surrounded by spinning disks of gas during their formation. B) Planets always tend to orbit their star in the same direction and approximately the same plane. C) Other solar systems will also have planets in the two basic categories of terrestrial and jovian. D) Other planetary systems will have far more numerous asteroids and comets than actual planets.

A

Based on its surface features, the most important event on Venus in the past billion years or so was A) a global "repaving" that erased essentially all the surface features that had existed earlier. B) the eruption of a giant volcano that formed one of Venus's "continents." C) the impact of an unusually large asteroid that left a deep scar on one side of the planet. D) the onset of mantle convection, which caused Venus's lithosphere to split into plates like those on Earth.

A

Current techniques can measure stellar motion to less than A) walking speed. B) running speed. C) freeway speed. D) cruising speed of an airplane. E) orbital speed of Jupiter.

A

Deep trenches in the ocean mark places where A) one plate slides under another, returning older crust to the mantle. B) plates pull apart, leaving great rifts in the crust. C) hot mantle material rises upward and spreads sideways, pushing the plates apart. D) plates push together, creating ocean mountain chains. E) plates slip sideways relative to one another.

A

Heat escapes from a planet's surface into space by thermal radiation. Planets radiate almost entirely in the wavelength range of the A) infrared. B) radio. C) visible. D) ultraviolet. E) none of the above

A

How did the lunar maria form? A) Large impacts fractured the Moon's lithosphere, allowing lava to fill the impact basins. B) The early bombardment created heat that melted the lunar surface in the regions of the maria. C) Volatiles escaping from the Moon's interior heated and eroded the surface in the regions of the maria. D) The giant impact that created the Moon left smooth areas that we call the maria. E) The maria are the result of gradual erosion by micrometeorites striking the Moon.

A

How do the jovian planet interiors differ? A) All have cores of about the same mass, but differ in the amount of surrounding hydrogen and helium. B) The core mass decreases with the mass of the planet. C) The composition changes from mostly ammonia in Jupiter and Saturn to mostly methane in Uranus and Neptune. D) The composition changes from mostly hydrogen in Jupiter and Saturn to mostly helium in Uranus and Neptune. E) All have about the same amount of hydrogen and helium but the proportion of rocks is greater in those planets closer to the Sun.

A

How do we expect that the first Earth-sized extrasolar planets will be discovered (if they exist)? A) by the transit technique from an observatory in space B) with photographs from a new generation of large, ground-based observatories C) by NASA's Terrestrial Planet Finder mission D) by the Doppler technique

A

How fast do plates move on Earth? A) a few centimeters per year B) a few millimeters per century C) a few kilometers per century D) quite fast, but only during earthquakes E) about 1 mile per hour

A

In essence, the nebular theory holds that A) our solar system formed from the collapse of an interstellar cloud of gas and dust. B) nebulae are clouds of gas and dust in space. C) the planets each formed from the collapse of its own separate nebula. D) the nebular theory is a discarded idea that imagined planets forming as a result of a near-collision between our Sun and another star.

A

In general, which things below are affected by a magnetic field? A) charged particles or magnetized materials (such as iron) B) rocks of all types C) iron-bearing minerals only D) bases and liquids

A

In general, which type of planet would you expect to cause the largest Doppler shift in the spectrum of its star? A) a massive planet that is close to its star B) a massive planet that is far from its star C) a low-mass planet that is close to its star D) a low-mass planet that is far from its star

A

In the context of planetary geology, what do we mean by outgassing? A) the release by volcanism of gases that had been trapped in a planetary interior B) the loss of atmospheric gas to outer space C) another name for a volcanic eruption D) the evaporation of water that adds water vapor (a gas) to an atmosphere

A

Jupiter's colors come in part from its three layers of clouds. Which of the following is not the primary constituent of one of Jupiter's cloud layers? A) clouds of sulfuric acid B) clouds of water C) clouds of ammonium hydrosulfide D) clouds of ammonia

A

Many scientists suspect that Venus has a stronger and thicker lithosphere than Earth. If this is true, which of the following could explain it? A) the high surface temperature that has "baked out" all the liquid water from Venus's crust and mantle B) the smaller size of Venus, which has allowed it to lose much more internal heat than Earth C) the slow rotation of Venus D) the apparent lack of plate tectonics on Venus

A

Most of the Moon's surface is densely covered with craters, but we find relatively few craters within the lunar maria. What can we conclude? A) The maria formed after the heavy bombardment ended. B) The maria formed within the past 1 billion years. C) The regions of the maria were hit by fewer impacts than the densely cratered regions. D) Erosion affects the maria more than it affects other regions of the Moon.

A

Olympus Mons is A) a huge shield volcano on Mars. B) a huge stratovolcano on Venus. C) a large lava plain on the Moon. D) a great canyon on Mars.

A

Olympus Mons is a A) shield volcano on Mars. B) stratovolcano on Mercury. C) large lava plain on the Moon. D) shield volcano on Venus. E) stratovolcano on the Moon.

A

Suppose we had a device that allowed us to see Earth's interior. If we looked at a typical region of the mantle, what would we see happening? A) not much—on human time scales, the mantle looks like solid rock B) hot molten rock rising upward throughout the mantle and cool, solid rock falling downward C) a rapid, up-and-down churning of the material in the mantle D) dense metals falling downward while low-density rock rises upward

A

Suppose you start with 1 kilogram of a radioactive substance that has a half-life of 10 years. Which of the following statements will be true after 20 years pass? A) You'll have 0.25 kilogram of the radioactive substance remaining. B) All the material will have completely decayed. C) You'll have 0.75 kilogram of the radioactive substance remaining. D) You'll have 0.5 kilogram of the radioactive substance remaining.

A

The belts and zones of Jupiter are A) alternating bands of rising and falling air at different latitudes. B) cyclonic and anticyclonic storms. C) names for different cloud layers on Jupiter. D) alternating regions of charged particles in Jupiter's magnetic field. E) the thermosphere and stratosphere respectively.

A

The choices below describe four hypothetical planets. Which one would you expect to have the hottest interior? (Assume the planets orbit a star just like the Sun and that they are all the same age as the planets in our solar system.) A) Size: same as the Moon. Distance from Sun: same as Mars. Rotation rate: once every 10 days. B) Size: twice as big as Earth. Distance from Sun: same as Mercury. Rotation rate: once every 6 months. C) Size: same as Mars. Distance from Sun: same as Earth. Rotation rate: once every 18 hours. D) Size: same as Venus. Distance from Sun: same as Mars. Rotation rate: once every 25 hours.

A

The choices below describe four hypothetical planets. Which one would you expect to have the most features of erosion? (Assume the planets orbit a star just like the Sun and that they are all the same age as the planets in our solar system.) A) Size: same as Venus. Distance from Sun: same as Mars. Rotation rate: once every 25 hours. B) Size: same as the Moon. Distance from Sun: same as Mars. Rotation rate: once every 10 days. C) Size: same as Mars. Distance from Sun: same as Earth. Rotation rate: once every 18 hours. D) Size: twice as big as Earth. Distance from Sun: same as Mercury. Rotation rate: once every 6 months.

A

The composition of a planet's atmosphere be measured during a transit by analyzing A) the excess absorption of starlight at specific wavelengths. B) the excess emission of starlight at specific wavelengths. C) the length and depth of the dip in light during the transit. D) the amplitude and period of the star's motion. E) the wobble in a star's position on the sky.

A

The main process by which heat flows upward through the lithosphere is A) conduction. B) convection. C) radiation. D) accretion. E) differentiation.

A

The reason that small planets tend to lose interior heat faster than larger planets is essentially the same as the reason that A) a large baked potato takes longer to cool than a small baked potato. B) gas bubbles form and rise upward in boiling water. C) Earth contains more metal than the Moon. D) thunderstorms tend to form on hot summer days.

A

The region of our solar system between Mercury and Mars has very few asteroids, while the region between Mars and Jupiter has many asteroids. Based on what you have learned, what is the most likely explanation for the lack of asteroids between Mercury and Mars? A) There were very few planetary leftovers in this region, because most of the solid material was accreted by the terrestrial planets as the planets formed. B) It was too hot for asteroids to form in this part of the solar system. C) Gravity was too weak to allow asteroids to form in this part of the solar system. D) All the asteroids that formed between Mercury and Mars later migrated to the asteroid belt between Mars and Jupiter.

A

The size and shape of a planet's orbit can be determined by A) the Doppler technique. B) transit observations. C) spectral measurements. D) knowing the planet's mass by any technique and applying Newton's version of Kepler's third law. E) gravitational microlensing.

A

The terrestrial planets are made almost entirely of elements heavier than hydrogen and helium. According to modern science, where did these elements come from? A) They were produced by stars that lived and died before our solar system was born. B) They were produced by gravity in the solar nebula as it collapsed. C) They have been present in the universe since its birth. D) They were made by chemical reactions in interstellar gas.

A

The transit method of planet detection works best for A) big planets in edge-on orbits around small stars. B) big planets in face-on orbits around small stars. C) small planets in edge-on orbits around big stars. D) small planets in face-on orbits around big stars. E) Earth-like planets in any orbit.

A

Uranus and Neptune have methane clouds but Jupiter and Saturn do not. Which factor explains why? A) Temperatures on Jupiter and Saturn are too high for methane to condense. B) Jupiter and Saturn do not contain any methane gas. C) The rapid rotation of Jupiter and Saturn prevents methane clouds from forming. D) The stronger gravity on Jupiter and Saturn pulls methane downward so that it can't form clouds.

A

What are the basic requirements for a terrestrial world to have a global magnetic field? A) a core layer of molten, convecting material and sufficiently rapid rotation B) a metal core and rapid rotation C) a metal core, a rocky mantle, and sufficiently rapid rotation D) a core that has a molten layer and a mantle that has convection

A

What atmospheric constituent is responsible for the blue color of Uranus and Neptune? A) methane B) hydrogen C) water D) ammonia

A

What do we mean by the frost line when we discuss the formation of planets in the solar nebula? A) It is a circle at a particular distance from the Sun, beyond which the temperature was low enough for ices to condense. B) It is another way of stating the temperature at which water freezes into ice. C) It marks the special distance from the Sun at which hydrogen compounds become abundant; closer to the Sun, there are no hydrogen compounds. D) It is the altitude in a planet's atmosphere at which snow can form.

A

What do we mean by the period of heavy bombardment in the context of the history of our solar system? A) the first few hundred million years after the planets formed, which is when most impact craters were formed B) the time before planetesimals finished accreting into planets, during which many growing planetesimals must have shattered in collisions C) the time during which heavy elements condensed into rock and metal in the solar nebula D) the period about 65 million years ago when an impact is thought to have led to the extinction of the dinosaurs

A

What do we mean when we say that the terrestrial worlds underwent differentiation? A) When their interiors were molten, denser materials sank toward their centers and lighter materials rose toward their surfaces. B) The five terrestrial worlds all started similarly but ended up looking quite different. C) Their surfaces show a variety of different geological features resulting from different geological processes. D) They lost interior heat to outer space.

A

What drives the motion of the tectonic plates on Earth? A) convection cells in the mantle B) lava flows in trenches along the sea floor C) the Coriolis force D) Earth's magnetic field E) tidal forces

A

What is an extrasolar planet? A) a planet that orbits a star that is not our own Sun B) a planet that is larger than the Sun C) a planet that is extra large compared to what we'd expect D) a planet that is considered an "extra," in that it was not needed for the formation of its solar system

A

What is differentiation in planetary geology? A) the process by which gravity separates materials according to density B) the process by which different types of minerals form a conglomerate rock C) any process by which a planet's surface evolves differently from another planet's surface D) any process by which one part of a planet's surface evolves differently from another part of the same planet's surface E) any process by which a planet evolves differently from its moons

A

What is the fundamental reason that Mars, unlike Earth, has become virtually geologically dead? A) its small size compared to Earth B) its large size compared to Earth C) its farther distance than Earth to the Sun D) its closer distance than Earth to the Sun E) its rapid rotation compared to Earth F) its slow rotation compared to Earth

A

What is the most important reason why an icy moon is more likely to be geologically active than a rocky moon of the same size? A) Ice has a lower melting point than rock. B) Ice is less rigid than rock. C) Ice contains more radioactive elements than rock. D) Ice is affected by tidal forces to a greater extent than rock. E) Ice is less dense than rock.

A

What is the primary basis upon which we divide the ingredients of the solar nebula into four categories (hydrogen/helium; hydrogen compound; rock; metal)? A) the temperatures at which various materials will condense from gaseous form to solid form B) the atomic mass numbers of various materials C) the locations of various materials in the solar nebula D) the amounts of energy required to ionize various materials

A

Which moon has the most substantial atmosphere? A) Titan B) Ganymede C) Io D) Europa E) Mimas

A

Which moon is considered likely to have a deep, subsurface ocean of liquid water? A) Europa B) Io C) Miranda D) Triton

A

Which of the following best describes the internal layering of Jupiter, from the center outward? A) core of rock, metal, and hydrogen compounds; thick layer of metallic hydrogen; layer of liquid hydrogen; layer of gaseous hydrogen; cloud layer B) core of rock and metal; mantle of lower density rock; upper layer of gaseous hydrogen; cloud layer C) solid rock core; layer of solid metallic hydrogen; layer of pure liquid hydrogen; cloud layer D) liquid core of hydrogen compounds; liquid hydrogen layer; metallic hydrogen layer; gaseous hydrogen layer; cloud layer

A

Which of the following best explains why many jovian moons have been more geologically active than the Moon or Mercury? A) Jovian moons are made mostly of ice that can melt or deform at lower temperatures than can the rock and metal that make up the Moon and Mercury. B) The jovian moons are considerably larger than the Moon and Mercury and therefore have retained much more internal heat. C) The jovian moons probably have far more internal heat generated by radioactive decay than do the Moon or Mercury. D) Because of their greater distances from the Sun, the jovian moons receive much less heat from the Sun.

A

Which of the following describes impact cratering? A) the excavation of bowl-shaped depressions by asteroids or comets striking a planet's surface B) the eruption of molten rock from a planet's interior to its surface C) the disruption of a planet's surface by internal stresses D) the wearing down or building up of geological features by wind, water, ice, and other phenomena of planetary weather

A

Which of the following gases is not a significant ingredient of the jovian planet atmospheres? A) carbon dioxide B) hydrogen C) helium D) water

A

Which of the following is an example of convection? A) warm air expanding and rising while cooler air contracts and fall B) different kinds of material separating by density, like oil and water C) rocks sinking in water D) gas bubbling upward through a liquid

A

Which of the following is not a line of evidence supporting the hypothesis that our Moon formed as a result of a giant impact? A) The Pacific Ocean appears to be a large crater—probably the one made by the giant impact. B) Computer simulations show that the Moon could really have formed in this way. C) The Moon's average density suggests it is made of rock much more like that of the Earth's outer layers than that of Earth as a whole. D) The Moon has a much smaller proportion of easily vaporized materials than Earth.

A

Which of the following is not an example of tectonics? A) the gradual disappearance of a crater rim as a result of wind and rain B) the formation of a cliff when the lithosphere shrinks C) the slow movement of Earth's lithospheric plates D) the stretching of the crust by underlying mantle convection

A

Which of the following is not generally true of all the terrestrial world lithospheres? A) The lithosphere is broken into a set of large plates that float upon the softer rock below. B) Rock in the lithosphere is stronger than rock beneath it. C) The lithosphere extends from somewhere in the mantle all the way to the surface. D) The thickness of the lithosphere depends on interior temperature, with cooler interiors leading to thicker lithospheres.

A

Which of the following lists the ingredients of the solar nebula from highest to lowest percentage of mass of the nebula? A) light gases (H, He), hydrogen compounds (H2O, CH4, NH3), rocks, metals B) hydrogen compounds (H2O, CH4, NH3), light gases (H, He), rocks, metals C) light gases (H, He), hydrogen compounds (H2O, CH4, NH3), metals, rocks D) hydrogen compounds (H2O, CH4, NH3), light gases (H, He), metals, rocks E) hydrogen compounds (H2O, CH4, NH3), rocks, metals, light gases (H, He)

A

Which of the following methods has not yet detected planets around other stars? A) detection of reflected light by the planet B) detecting periodic Doppler shifts in a star's spectrum C) detecting periodic shifts in the position of a star on the sky D) detecting the decrease in light as a planet transits a star E) All of the above have succeeded.

A

Which of the following most likely explains why Jupiter's interior releases so much heat? A) Jupiter is contracting very gradually B) heat from radioactive decay C) a slow rate of nuclear fusion in Jupiter's core D) tidal heating

A

Which planet can we see occasionally transit across the face of the Sun? A) Mercury B) Mars C) Jupiter D) Uranus E) all of the above

A

Which statement about Io is true? A) It is the most volcanically active body in our solar system. B) It is thought to have a deep, subsurface ocean of liquid water. C) It is the largest moon in the solar system. D) It is the only moon in the solar system with a thick atmosphere.

A

Why are terrestrial planets denser than jovian planets? A) Only dense materials could condense in the inner solar nebula. B) The Sun's gravity gathered dense materials into the inner solar system. C) Gravity compresses terrestrial planets to a higher degree, making them denser. D) Actually, the jovian planets are denser than the terrestrial planets.

A

Why are there fewer large craters on the seafloor than on the continents? A) The seafloor crust is younger than the continental crust. B) The oceans slow large impactors and prevent them from making craters. C) The oceans erode away craters faster than erosion processes on land. D) Large impactors primarily strike land masses. E) Large impactors aim for life-forms such as dinosaurs.

A

Why are there fewer large impact craters on the Earth's seafloor than on the continents? A) Seafloor crust is younger than continental crust, so it has had less time in which to suffer impacts. B) The oceans slow large impactors and prevent them from making craters. C) Erosion erases impact craters must faster on the ocean bottom than on land. D) Most impacts occur on the land.

A

Why do Uranus and Neptune have blue methane clouds but Jupiter and Saturn do not? A) Methane does not condense into ice in the warmer atmospheric temperatures of Jupiter and Saturn. B) Methane did not exist in the solar nebula at the radii of Jupiter and Saturn when the planets formed. C) The greater gravitational force of Jupiter and Saturn prevents the methane from rising to the upper edges of the atmosphere. D) Methane reacts with the abundant ammonia clouds in Jupiter and Saturn. E) The relatively slow rotation of Uranus and Neptune allows methane to migrate to higher levels in the atmosphere and condense into clouds.

A

Why do astronomers believe Triton may have been a planet that was captured by Neptune? A) It orbits Neptune in the opposite direction of Neptune's rotation. B) It is too large to have been formed in the jovian nebula that formed Neptune. C) It has an atmosphere and a measurable greenhouse effect. D) It undergoes seasonal changes. E) It is colder than any other moon or planet.

A

Why do astronomers believe that Triton is a captured moon? A) Triton orbits Neptune in a direction opposite that of Neptune's rotation. B) Triton is very small and potato-shaped, which is common of captured moons. C) Triton is too large to have been formed in the "miniature solar nebula" thought to have surrounded Neptune in its very early history. D) Triton appears to be made mostly of ice.

A

Why do astronomers think Miranda has such an unusual surface? A) It underwent an episode of tidal heating in the past. B) It was squashed by a giant impact. C) It formed from the remains of a giant impact relatively recently. D) Its surface is covered with a powdery dust from micrometeorite impacts. E) Its low temperature affects the colors of its surface ice.

A

Why do we say that the Doppler technique gives the planet's "minimum mass"? A) The size of the Doppler shift that we detect depends on whether the planet's orbit is tilted. B) The size of the Doppler shift that we detect depends on knowing the star's mass, which can be very uncertain. C) Extrasolar planets are always increasing in mass. D) Doppler measurements are very difficult, producing noisy data that often cause astronomers to underestimate a planet's mass.

A

Why does Jupiter have several distinct cloud layers? A) Different layers represent clouds made of gases that condense at different temperatures. B) Different layers represent the various regions where the temperature is cool enough for liquid water to condense. C) Different gases are present at different altitudes in Jupiter's atmosphere. D) Winds prevent clouds from forming at some altitudes, so we see clouds only at the other altitudes. E) Clouds form randomly, so on average there are always several layers.

A

Why does Jupiter have three distinct layers of clouds? A) The three layers represent clouds made of gases that condense at different temperatures. B) Jupiter has three different types of wind that each make a different type of cloud. The three layers reflect regions of Jupiter's atmosphere with different overall chemical compositions. C) Clouds form randomly, so on average there are always three layers.

A

Why is Neptune denser than Saturn? A) It has a different composition than Saturn, including a higher proportion of hydrogen compounds and rocks. B) It has a greater proportion of hydrogen than Saturn. C) The extra mass of Neptune compresses its interior to a greater extent than that of Saturn. D) Its hydrogen is molecular, whereas Saturn's hydrogen is atomic. E) It is not denser than Saturn.

A

Why is Saturn almost as big as Jupiter, despite its smaller mass? A) Jupiter's greater mass compresses it more, thus increasing its density. B) Saturn's rings make the planet look bigger. C) Saturn is further from the Sun, thus cooler, and therefore less compact. D) Saturn has a larger proportion of hydrogen and helium than Jupiter, and is therefore less dense. E) Jupiter's strong magnetic field constrains its size.

A

Why is continental crust lower in density than seafloor crust? A) Continental crust is made from remelted seafloor crust and therefore only the lower-density material rises to form it. B) Continental crust is made from volcanic rock called basalt, which is lower in density than what the seafloor crust is made from. C) Continental crust is made of rock, while seafloor crust has more metals. D) Seafloor crust is more compact due to the weight of the oceans, but it is made of the same material as the continental crust. E) Continental crust is actually denser than seafloor crust.

A

According to modern science, what was the approximate chemical composition of the solar nebula? A) 50% hydrogen and helium, 50% everything else B) 98% hydrogen and helium, 2% everything else C) 98% hydrogen, 2% helium D) roughly equal proportions of hydrogen, helium, water, and methane

B

According to our present theory of solar system formation, which of the following statements about the growth of terrestrial and jovian planets is not true? A) Both types of planet begun with planetesimals growing through the process of accretion, but only the jovian planets were able to capture hydrogen and helium gas from the solar nebula. B) The jovian planets began from planetesimals made only of ice, while the terrestrial planets began from planetesimals made only of rock and metal. C) Swirling disks of gas, like the solar nebula in miniature, formed around the growing jovian planets but not around the growing terrestrial planets. D) The terrestrial planets formed inside the frost line of the solar nebula and the jovian planets formed beyond it.

B

The astrometric technique of planet detection works best for A) large planets around nearby stars. B) massive planets around nearby stars. C) large planets around distant stars. D) massive planets around distant stars. E) planets in edge-on orbits.

B

A planet is detected via the Doppler technique. The velocity change of the star is a measure of A) the planet's size and density. B) the planet's mass and orbital distance. C) the planet's mass and composition. D) the planet's orbital period and eccentricity. E) the planet's size and orbital distance.

B

A planet's density can be measured by combining A) Doppler and astrometric observations. B) Doppler and transit observations. C) spectral observations of the planet's atmosphere. D) any method that measures the gravitational tug of the planet on the star. E) direct imaging from the new generation of space telescopes.

B

According to our present theory of solar system formation, why were solid planetesimals able to grow larger in the outer solar system than in the inner solar system? A) because the Sun's gravity was stronger in the outer solar system, allowing more solid material to collect B) because only metal and rock could condense in the inner solar system, while ice also condensed in the outer solar system C) because gas in the outer solar system contained a larger proportion of rock, metal, and hydrogen compounds than the gas in the inner solar system D) because only the outer planets captured hydrogen and helium gas from the solar nebula

B

According to our theory of solar system formation, why did Uranus and Neptune end up to be much less massive than Jupiter and Saturn? A) Ices were able to condense at the distance of Jupiter and Saturn, but only rock and metal could condense at the distances of Uranus and Neptune. B) Particles in the solar nebula were more spread out at greater distances, so that accretion took longer and there was less time to pull in gas before the solar wind cleared the nebula. C) The colder gas in the outer regions of the solar nebula had less gravity and therefore could not gather up into such large balls as it could closer in. D) The size differences are thought to be a random coincidence.

B

According to the nebular theory, how did the Kuiper belt form? A) It is material left over from the interstellar cloud that never contracted with the rest of the gases to form the solar nebula. B) It is made of planetesimals that formed beyond Neptune's orbit and never accreted to form a planet. C) It consists of objects that fragmented from the protosun during a catastrophic collision early in the formation of the solar system. D) It is made of planetesimals between the orbits of Mars and Jupiter that never formed into a planet. E) It is made of planetesimals formed in the outer solar system that were flung into distant orbits by encounters with the jovian planets.

B

All the following statements are true. Which one is most important in explaining the tremendous tidal heating that occurs on Io? A) Io is the closest to Jupiter of Jupiter's large moons. B) Io orbits Jupiter on an elliptical orbit, due to orbital resonances with other satellites. C) Io exhibits synchronous rotation, meaning that its rotation period and orbital period are the same. D) Io orbits Jupiter in the Io torus, and therefore has a surface that is bombarded by many charged particles.

B

As of 2008, most known extrasolar planets have been discovered by A) the astrometric technique. B) the Doppler technique. C) the transit technique. D) the Hubble Space Telescope.

B

Current evidence suggests that many massive jovian planets orbit at very close orbital distances to their stars. How do we think these planets ended up on these close orbits? A) These planets are jovian in nature and were able to form close to their stars because their solar nebulas were very cold in temperature. B) These planets migrated inward after being born on orbits much farther from their stars. C) Despite their large masses, these planets are terrestrial in nature and therefore could form in their inner solar systems. D) These planets were captured from other solar systems.

B

How does seafloor crust differ from continental crust? A) Seafloor crust is thicker, older, and higher in density. B) Seafloor crust is thinner, younger, and higher in density. C) Seafloor crust is thinner, older, and lower in density. D) Seafloor crust is thicker, older, and lower in density. E) Seafloor crust is thicker, younger, and lower in density.

B

How much energy does Jupiter emit compared with how much it receives from the Sun? A) It emits 10 times as much. B) It emits twice as much. C) It emits half as much. D) It emits 10 percent as much. E) It emits 1 percent as much.

B

In essence, most of the extrasolar planets discovered to date have been found by A) closely examining very high-resolution photographs of other star systems. B) observing a star carefully enough to notice that it is experiencing a gravitational tug caused by an unseen planet. C) identifying spectral lines that look like what we expect to see from a planet rather than a star. D) observing mini-eclipses of a star as an unseen planet passes in front of it.

B

Many meteorites appear to have formed very early in the solar system's history. How do these meteorites support our theory about how the terrestrial planets formed? A) The meteorites sizes are just what we'd expect if metal and rock condensed and accreted as our theory suggests. B) The meteorites appearance and composition is just what we'd expect if metal and rock condensed and accreted as our theory suggests. C) Their overall composition is just what we believe the composition of the solar nebula to have been: mostly hydrogen and helium. D) Their appearance and composition matches what we observe in comets today, suggesting that meteorites were once pieces of icy planetesimals.

B

Most of the planets discovered around other stars A) are more massive than Earth and orbit very far from the star. B) are more massive than Earth and orbit very close to the star. C) are less massive than Earth and orbit very far from the star. D) are less massive than Earth and orbit very close to the star. E) are found around neutron stars.

B

Recent evidence suggests that Mars once had a global magnetic field. Assuming this is true, which of the following could explain why Mars today lacks a global magnetic field like that of Earth? A) Mars rotates much slower than Earth. B) Mars's interior has cooled so much its molten core layer no longer undergoes convection. C) The Martian core is made of rock, while Earth's core is made of metal. D) Mars is too far from the Sun to have a global magnetic field.

B

Shallow-sloped shield volcanoes are made from lava that A) is as runny as liquid water. B) has a medium viscosity. C) has a high viscosity. D) can have any viscosity.

B

Suppose we use a baseball to represent Earth. On this scale, the other terrestrial worlds (Mercury, Venus, the Moon, and Mars) would range in size approximately from that of A) a dust speck to a golf ball. B) a golf ball to a baseball. C) a dust speck to a basketball. D) a golf ball to a beach ball.

B

Suppose you could float in space just a few meters above Saturn's rings. What would you see as you looked down on the rings? A) a solid, shiny surface, looking much like a piece of a DVD but a lot bigger B) countless icy particles, ranging in size from dust grains to large boulders C) dozens of large "moonlets" made of metal and rock, each a few kilometers across D) Nothing—up close, the rings would be so completely invisible that you'd have no way to know they are there. They can be seen only from a distance

B

The cores of the terrestrial worlds are made mostly of metal because A) the terrestrial worlds as a whole are made mostly of metal. B) metals sunk to the centers a long time ago when the interiors were molten throughout. C) the core contained lots of radioactive elements that decayed into metals. D) over billions of years, convection gradually brought dense metals downward to the core.

B

The geysers and hot springs of Yellowstone National Park result from A) thin continental crust separating and creating a rift valley. B) plumes of hot mantle rising in a hot spot within a plate. C) plates that have slipped sideways relative to each other, creating a fault. D) a plate that has run up against an existing continental plate. E) a fault.

B

The processes responsible for virtually all surface geology are A) convection, conduction, and radiation. B) impact cratering, volcanisms, tectonics, and erosion. C) accretion, differentiation, and radioactive decay. D) eruptions, lava flows, and outgassing.

B

The relatively few craters that we see within the lunar maria A) were formed by impacts that occurred before those that formed most of the craters in the lunar highlands. B) were formed by impacts that occurred after those that formed most of the craters in the lunar highlands. C) were created by the same large impactor that led to the formation of the maria. D) are volcanic in origin, rather than from impacts. E) are sinkholes that formed when sections of the maria collapsed.

B

The three principal sources of internal heat of terrestrial planets are A) conduction, differentiation, and accretion. B) accretion, differentiation, and radioactivity. C) accretion, differentiation, and eruption. D) convection, differentiation, and eruption. E) conduction, convection, and eruption.

B

What are the two geological features that appear to set Earth apart from all the other terrestrial worlds? A) shield volcanoes and plate tectonics B) plate tectonics and widespread erosion C) significant volcanism and tectonics D) mantle convection and a thick atmosphere

B

What do we mean by accretion in the context of planet formation? A) the formation of moons around planets B) the growth of planetesimals from smaller solid particles that collided and stuck together C) the solidification of ices, rocks, and metal from the gas of the solar nebular D) the growth of the Sun as the density of gas increased in the center of the solar nebula

B

What happened during the accretion phase of the early solar system? A) Atoms and molecules in the gas bonded together and solidified. B) Particles grew by colliding and sticking together. C) The solar nebula differentiated into metals inside of the frost line and ices beyond. D) Large planetesimals captured atmospheres from the solar nebula. E) Earth gained its oceans from icy planetesimal capture.

B

What is basalt? A) any substance that evaporates easily and is a gas, liquid, or ice on Earth B) a type of rock that makes relatively low-viscosity lava C) a type of metal that tends to create stratovolcanoes when eruptions occur D) a type of mineral that is the main ingredient of sea salt E) another name for lava

B

What is the Cassini division of Saturn's rings? A) a dark ring, visible from Earth, composed of dark, dusty particles B) a large gap, visible from Earth C) the imaginary circle marking the halfway point of Saturn's rings D) the widest ring of Saturn, located between two large ring gaps E) the most opaque ring of Saturn, made of highly reflective ice particles

B

What is the Great Red Spot? A) a hurricane that comes and goes on Jupiter B) a long-lived, high-pressure storm on Jupiter C) a place where reddish particles from Io impact Jupiter's surface D) a region on Jupiter where the temperature is so high that the gas glows with red visible light

B

What is the most abundant gas in Titan's atmosphere? A) methane B) nitrogen C) hydrogen compounds D) oxygen E) argon

B

What kind of material in the solar nebula could remain solid at temperatures as high as 1,500 K, such as existed in the inner regions of the nebula? A) rocks B) metals C) silicon-based minerals D) hydrogen compounds E) molecules such as methane and ammonia

B

When we say that a liquid has a high viscosity, we mean that it A) is runny like water. B) flows slowly like honey. C) is very dark in color. D) is very light in color. E) conducts electricity.

B

Which moon has a thick atmosphere made mostly of nitrogen? A) Triton B) Titan C) Ganymede D) Europa

B

Which new idea has been added into our theory of solar system formation as a result of the discoveries of extrasolar planets? A) In addition to the categories of terrestrial and jovian, there must be an "in-between" category of planet that has the mass of a jovian planet but the composition of a terrestrial planet. B) Jovian planets can migrate from the orbits in which they are born. C) In some star systems, it is possible for jovian planets to form in the inner solar system and terrestrial planets to form in the outer solar system. D) Some of the "exceptions to the rules" in our own solar system are likely to have been the result of giant impacts.

B

Which of the following best describes convection? A) It is the process by which rocks sink in water. B) It is the process in which warm material expands and rises while cool material contracts and falls. C) It is the process in which warm material gets even warmer and cool material gets even cooler. D) It is the process in which a liquid separates according to density, such as oil and water separating in a jar. E) It is the process in which bubbles of gas move upward through a liquid of the same temperature.

B

Which of the following best explains why we can rule out the idea that planets are usually formed by near-collisions between stars? A) Studies of the trajectories of nearby stars relative to the Sun show that the Sun is not in danger of a near-collision with any of them. B) Stellar near-collisions are far too rare to explain all the planets now known to orbit nearby stars. C) A near collision might have created planets, but it could not have created moons, asteroids, or comets. D) A near collision should have left a trail of gas extending out behind the Sun, and we see no evidence of such a trail.

B

Which of the following best why we see horizontal "stripes" in photographs of Jupiter and Saturn? A) The dark and light stripes correspond to alternating bands of different chemical composition. B) The light stripes are regions of high clouds, and the dark stripes are regions where we can see down to deeper, darker clouds. C) There are three different color stripes corresponding to the three different types of clouds found on these planets. D) Dark stripes are those in which there is a stratosphere and light stripes are those with no stratosphere.

B

Which of the following describes volcanism? A) the excavation of bowl-shaped depressions by asteroids or comets striking a planet's surface B) the eruption of molten rock from a planet's interior to its surface C) the disruption of a planet's surface by internal stresses D) the wearing down or building up of geological features by wind, water, ice, and other phenomena of planetary weather

B

Which of the following is not expected for a "hot Jupiter" that orbits 0.05 AU from its star? A) cloudtop temperatures over 1000 K B) intense volcanism C) clouds made of rock dust D) density similar to or lower than Jupiter's

B

Which of the following most likely explains why Venus does not have a strong magnetic field? A) It does not have a metallic core. B) Its rotation is too slow. C) It is too close to the Sun. D) It is too large. E) It has too thick an atmosphere.

B

Which of the following statements comparing the jovian interiors is not thought to be true? A) They all have cores of roughly the same mass. B) They all have the same exact set of internal layers, though these layers differ in size. C) They all have cores that contain at least some rock and metal. D) Deep inside them, they all have pressures far higher than that found on the bottom of the ocean on Earth.

B

Which of the following statements is not true about the planets so far discovered around other stars? A) Most of them are much more massive than Earth. B) Photographs reveal that most of them have atmospheres much like that of Jupiter. C) Many of them orbit closer to their star than Jupiter orbits the Sun. D) Many of them have been discovered by observing Doppler shifts in the spectra of the stars they orbit.

B

Which of the terrestrial worlds has the strongest magnetic field? A) Mars B) Earth C) the Moon D) Venus E) Mercury

B

Why did the solar nebula heat up as it collapsed? A) Nuclear fusion occurring in the core of the protosun produced energy that heated the nebula. B) As the cloud shrank, its gravitational potential energy was converted to kinetic energy and then into thermal energy. C) Radiation from other nearby stars that had formed earlier heated the nebula. D) The shock wave from a nearby supernova heated the gas. E) Collisions among planetesimals generated friction and heat.

B

Why do we think Mercury has so many tremendous cliffs? A) They were probably carved in Mercury's early history by running water. B) They were probably formed by tectonic stresses when the entire planet shrank as its core cooled. C) They probably formed when a series of large impacts hit Mercury one after the other. D) They are almost certainly volcanic in origin, carved by flowing lava. E) They represent one of the greatest mysteries in the solar system, as no one has suggested a reasonable hypothesis for their formation.

B

Why does Titan have such a nitrogen-rich atmosphere? A) It was formed that way in the solar nebula. B) The nitrogen comes from the breakup of ammonia (NH3) by solar radiation and subsequent thermal escape of the hydrogen. C) The nitrogen was formed from the chemical reaction of sulphuric acid with surface rocks. D) Through the impact of nitrogen rich comets during the early solar system. E) The nitrogen was created through a chain of fusion reactions in Titan's core.

B

Why is Jupiter denser than Saturn? A) It is made of a different composition than Saturn, including a higher proportion of hydrogen compounds and rocks. B) The extra mass of Jupiter compresses its interior to a greater extent than that of Saturn. C) Its core is much larger than Saturn's. D) It has a greater proportion of helium to hydrogen compared to Saturn. E) It is unknown why this is so.

B

You observe a star very similar to our own Sun in size and mass. This star moves very slightly back and forth in the sky once every four months, and you attribute this motion to the effect of an orbiting planet. What can you conclude about the orbiting planet? A) The planet must have a mass about the same as the mass of Jupiter. B) The planet must be closer to the star than Earth is to the Sun. C) The planet must be farther from the star than Neptune is from the Sun. D) You do not have enough information to say anything at all about the planet.

B

The four Galilean moons around Jupiter are A) all made of rock. B) all made of ice. C) a mixture of rock and ice. D) very similar to asteroids. E) hydrogen and helium gas.

C

About how many extrasolar planets have been discovered (as of 2008)? A) fewer than 10 B) between 10 and 100 C) between 100 and 1,000 D) more than 1,000

C

According to our present theory of solar system formation, how did Earth end up with enough water to make oceans? A) The water was mixed in the other materials in the planetesimals that accreted at our distance from the Sun. B) The water was formed by chemical reactions among the minerals in the Earth's core. C) The water was brought to the forming Earth by planetesimals that accreted beyond the orbit of Mars. D) Earth formed in the relatively narrow region of the solar nebular in which liquid water was plentiful.

C

According to our present theory of solar system formation, which of the following lists the major ingredients of the solar nebula in order from the most abundant to the least abundant? A) hydrogen compounds; hydrogen and helium gas; metal; rock B) hydrogen and helium gas; rock; metal; hydrogen compounds C) hydrogen and helium gas; hydrogen compounds; rock; metal D) hydrogen, water, methane, helium

C

According to our theory of solar system formation, where did the comets of the Oort cloud form? A) in the inner solar system B) far beyond the orbit of Pluto C) in the region of the jovian planets D) in the asteroid belt

C

The lithosphere of a planet is the layer that consists of A) material above the crust. B) material between the crust and the mantle. C) the rigid rocky material of the crust and uppermost portion of the mantle. D) the softer rocky material of the mantle. E) the lava that comes out of volcanoes.

C

According to our theory of solar system formation, why do all the planets orbit the Sun in the same direction and in nearly the same plane? A) The original solar nebula happened to be disk-shaped by chance. B) Any planets that once orbited in the opposite direction or a different plane were ejected from the solar system. C) The laws of conservation of energy and conservation of angular momentum ensure that any rotating, collapsing cloud will end up as a spinning disk. D) The Sun formed first, and as it grew in size it spread into a disk, rather like the way a ball of dough can be flattened into a pizza by spinning it. E) Luck explains it, as we would expect that most other solar systems would not have all their planets orbiting in such a pattern.

C

According to the nebular theory, what are asteroids and comets? A) They are the shattered remains of collisions between planets. B) They are the shattered remains of collisions between moons. C) They are leftover planetesimals that never accreted into planets. D) They are chunks of rock or ice that condensed long after the planets and moons had formed. E) They are chunks of rock or ice that were expelled from planets by volcanoes.

C

Approximately how many other planetary systems have been discovered to date? A) ten B) a hundred C) a thousand D) ten thousand E) a million

C

From center to surface, which of the following correctly lists the interior layers of a terrestrial world? A) mantle, core, crust B) mantle, crust, core C) core, mantle, crust D) core, crust, lithosphere

C

How do scientists determine the age of the solar system? A) radiometric dating of Moon rocks B) radiometric dating of the oldest Earth rocks C) radiometric dating of meteorites D) Theoretical calculations tell us how long it has taken the planets to evolve to their present forms.

C

How do we think the "hot Jupiters" around other stars were formed? A) They formed as gas giants close to the star in the same orbits that they are seen today. B) They formed as dense, rocky planets close to the star in the same orbits that they are seen today. C) They formed as gas giants beyond the frost line and then migrated inwards. D) Many planets were formed around the star but coalesced into a single planet close in. E) They spun off from the young star when it was rapidly rotating.

C

How does seafloor crust differ from continental crust? A) Seafloor crust is thicker, older, and higher in density. B) Seafloor crust is thicker, younger, and lower in density. C) Seafloor crust is thinner, younger, and higher in density. D) Seafloor crust is thinner, older, and lower in density.

C

How does the strength of Jupiter's magnetic field compare to that of Earth's magnetic field? A) Jupiter's magnetic field strength is about the same as Earth's. B) Jupiter's magnetic field is about twice as strong as Earth's. C) Jupiter's magnetic field is about 20,000 times as strong as Earth's. D) Jupiter's magnetic field is much weaker than Earth's.

C

How large is an impact crater compared to the size of the impactor? A) the same size B) 10-20 percent larger C) 10 times larger D) 100 times larger E) 1,000 times larger

C

How long, approximately, do geologists estimate it takes for the entire seafloor to be replaced due to plate tectonics? A) 2 million years B) 20 million years C) 200 million years D) 2 billion years E) longer than the age of the solar system

C

If every star had an Earth-like planet in an Earth-like orbit, how many could be detected by a transit? A) 1 in 2 B) 1 in 20 C) 1 in 200 D) 1 in 2,000 E) 1 in 20,000

C

On average, how fast do the plates move on Earth? A) about 1 mile per hour B) a few kilometers per year C) a few centimeters per year D) a few millimeters per century

C

Planets detected via the Doppler technique have been mostly A) Earth-mass, in Earth-like orbits. B) Jupiter-mass, in Jupiter-like orbits. C) Jupiter-mass, in very close orbits. D) Earth-mass, in very close orbits. E) a wide range of masses, in edge-on orbits.

C

Ridges in the middle of the ocean are places where A) one plate slides under another, returning older crust to the mantle. B) hot mantle material rises upward, creating volcanic islands. C) hot mantle material rises upward and spreads sideways, pushing the plates apart. D) plates push together, creating ocean mountain chains. E) plates slip sideways relative to one another.

C

Steep-sided stratovolcanoes are made from lava that A) is as runny as liquid water. B) has a medium viscosity. C) has a high viscosity. D) can have any viscosity.

C

Suppose you find a rock that contains 10 micrograms of radioactive potassium-40, which has a half-life of 1. 25 billion years. By measuring the amount of its decay product (argon-40) present in the rock, you conclude that there must have been 80 micrograms of potassium-40 when the rock solidified. How old is the rock? A) 1.25 billion years B) 2.5 billion years C) 3.75 billion years D) 5.0 billion years

C

The astrometric technique looks for planets with careful measurements of a star's A) brightness. B) velocity towards or away from us. C) position in the sky. D) all of the above

C

The choices below describe four hypothetical planets. Which one's surface would you expect to be most crowded with impact craters? (Assume the planets orbit a star just like the Sun and that they are all the same age as the planets in our solar system.) A) Size: twice as big as Earth. Distance from Sun: same as Mercury. Rotation rate: once every 6 months. B) Size: same as Mars. Distance from Sun: same as Earth. Rotation rate: once every 18 hours. C) Size: same as the Moon. Distance from Sun: same as Mars. Rotation rate: once every 10 days. D) Size: same as Venus. Distance from Sun: same as Mars. Rotation rate: once every 25 hours.

C

The depth of the dip in a star's brightness due to the transit of a planet depends most directly on A) the planet's mass. B) the planet's density. C) the planet's size. D) the size of the planet's orbit. E) the eccentricity of the planet's orbit.

C

The energy in the atmospheres of most of the jovian planets comes A) almost entirely from the Sun. B) almost entirely from their interiors. C) both the Sun and their interiors, in roughly equal proportions. D) tidal heating.

C

The Doppler technique for planet detection has found Earth-like planets around nearby Sun-like stars.

False

The major processes that heat the interiors of the terrestrial worlds are A) (1) Heat deposited as the planets were built from planetesimals; (2) heat of accretion; (3) heat that came from the gravitational potential energy of incoming planetesimals. B) (1) Heat of accretion; (2) heat from convection; (3) heat from thermal radiation. C) (1) Heat deposited as the planets were built from planetesimals; (2) heat deposited as the planets underwent differentiation; (3) heat released by radioactive decay. D) (1) Volcanism; (2) tectonics; (3) erosion.

C

The polar caps on Mars are composed of A) pure solid carbon dioxide. B) pure water ice. C) mostly solid carbon dioxide and some water ice. D) mostly water ice and some solid carbon dioxide. E) There are no polar caps on Mars.

C

The reason that most extrasolar planets are found close to their parent stars is A) the planets reflect more light the closer they are to the star. B) more of the starlight is blocked by the planet when it transits the star. C) the amount and frequency of the star's motion are both higher. D) the closer to a star, the hotter and therefore brighter the planet is. E) planets that are close to a star are heated up and therefore larger.

C

The terrestrial planet cores contain mostly metal because A) the entire planets are made mostly of metal. B) metals condensed first in the solar nebula and the rocks then accreted around them. C) metals sank to the center during a time when the interiors were molten throughout. D) radioactivity created metals in the core from the decay of uranium. E) convection carried the metals to the core.

C

To date, we've found very few planets orbiting their stars at distances comparable to the distances of the jovian planets in our solar system. Why do astronomers think this is the case? A) Planets at such distances are extremely rare. B) No known technique can detect planets at such large distances. C) We have not yet been searching for planets at such distances for a long enough time. D) Planets at such distances are probably very low in mass.

C

Viewed from afar, the transit of Earth would cause the Sun's brightness to dim by approximately one part in A) 100. B) 1,000. C) 10,000. D) 100,000. E) a million.

C

Volcanism is more likely on a planet that A) is closer to the Sun. B) is struck often by meteors and solar system debris. C) has high internal temperatures. D) doesn't have an atmosphere or oceans.

C

What are the two main differences between extrasolar planetary systems discovered to date and our Solar System? A) extrasolar planets tend to be more massive and dense than Jupiter B) extrasolar planet orbits tend to be more eccentric and inclined than in our Solar System C) extrasolar planet orbits tend to be closer and more eccentric than in our Solar System D) extrasolar planet orbits tend to be closer and more circular than in our Solar System E) extrasolar planets tend to be bigger and denser than Jupiter

C

What information does the Doppler technique give about an extrasolar planet? A) the planet's radius B) the planet's density C) the planet's minimum mass D) all of the above

C

What is astrometry? A) measuring distances to stars B) searching for planets around stars C) measuring the positions of stars on the sky D) measuring the velocities of stars via the Doppler effect E) using metric units for distance (e.g. meters rather than light years)

C

What is the closest that extrasolar planets have been found to their stars? A) nearer to their stars than Earth to the Sun B) nearer to their stars than Saturn to the Sun C) nearer to their stars than Mercury to our Sun D) unknown: we do not know the distance with enough accuracy to say

C

What is the giant impact hypothesis for the origin of the Moon? A) The Moon formed when two gigantic asteroids collided with one another. B) The Moon originally was about the same size as Earth, but a giant impact blasted most of it away so that it ended up much smaller than Earth. C) The Moon formed from material blasted out of the Earth's mantle and crust by the impact of a Mars-size object. D) The Moon formed just like Earth, from accretion in the solar nebula.

C

What is the most likely reason that there are no giant planets beyond Neptune? A) Any planets forming beyond Neptune would have drifted out of the solar system due to the weakness of the Sun's gravity at this distance. B) There was no material to create planetesimals beyond the orbit of Neptune. C) By the time planetesimals grew to a large enough mass to hold onto an atmosphere, the solar nebula had been blown away. D) Any planet forming beyond Neptune's orbit would have been scattered outside of the solar system by gravitational encounters. E) There may be, but they would be so faint that astronomers have not found them yet.

C

What percentage of the mass of the solar nebula consisted of elements other than hydrogen and helium? A) 0 percent B) 0.1 percent C) 2 percent D) 20 percent E) 80 percent

C

What process has shaped Earth's surface more than any other? A) impact cratering B) volcanism C) plate tectonics D) erosion E) acid rain

C

What type of stresses broke Earth's lithosphere into plates? A) impacts of asteroids and planetesimals B) internal temperature changes that caused the crust to expand and stretch C) the circulation of convection cells in the mantle, which dragged against the lithosphere D) cooling and contracting of the planet's interior, which caused the mantle and lithosphere to be compressed E) volcanism, which produced heavy volcanoes that bent and cracked the lithosphere

C

What was the frost line of the solar system? A) the distance from the Sun where temperatures were low enough for metals to condense, between the Sun and the present-day orbit of Mercury B) the distance from the Sun where temperatures were low enough for rocks to condense, between the present-day orbits of Mercury and Venus C) the distance from the Sun where temperatures were low enough for hydrogen compounds to condense into ices, between the present-day orbits of Mars and Jupiter D) the distance from the Sun where temperatures were low enough for asteroids to form, between the present-day orbits of Venus and Earth E) the distance from the Sun where temperatures were low enough for hydrogen and helium to condense, between the present-day orbits of Jupiter and Saturn

C

The Moon probably formed at the same time that Earth formed, rather like the formation of a double planet.

False

What would happen to Jupiter if we could somehow double its mass? A) Its density would decrease and its diameter would double. B) Its density would stay about the same and its volume would double. C) Its density would increase but its diameter would barely change. D) It would become a star, with nuclear fusion in its core.

C

What would happen to the planets in a solar system where the central star did not have a strong wind? A) One planet would grow to dominate all the others and gravitationally eject them out of the system. B) All planets would continue to grow to large sizes but their orbits would be unchanged. C) The gas in the solar nebula would create a drag on the planets and their orbits would migrate inwards. D) The gas in the solar nebula would create a drag on the planets and their orbits would migrate outwards. E) Nothing, the star does not affect the process of planet formation.

C

Where did the elements heavier than hydrogen and helium come from? A) They were produced in the Big Bang. B) They evolved from hydrogen and helium shortly after the Big Bang. C) They were produced inside stars. D) They were produced inside dense interstellar gas. E) all of the above

C

Which internal energy source is the most important in continuing to heat the terrestrial planets today? A) accretion B) differentiation C) radioactivity D) tidal heating E) all of the above

C

Which jovian planet should have the most extreme seasonal changes? A) Jupiter B) Saturn C) Uranus D) Neptune

C

Which large jovian moon is thought to have been captured into its present orbit? A) Callisto B) Titan C) Triton D) Io

C

Which of the following describes tectonics? A) the excavation of bowl-shaped depressions by asteroids or comets striking a planet's surface B) the eruption of molten rock from a planet's interior to its surface C) the disruption of a planet's surface by internal stresses D) the wearing down or building up of geological features by wind, water, ice, and other phenomena of planetary weather

C

Which of the following does not provide evidence that Mars once had flowing water? A) the presence of what looks like dried-up riverbeds B) the presence of impact craters that appear to have formed in mud C) the presence of vast canals discovered in the late 1800s by Giovanni Schiaparelli and mapped by Percival Lowell D) rocks of many different types jumbled together, as would occur if there had once been a great flood in the region, found by the Mars Pathfinder E) some very old craters that appear to have been eroded by rain

C

Which of the following has virtually no effect on the structure of a planet? A) its composition B) its size C) its magnetic field D) its mass

C

Which of the following is a consequence of the discovery of hot Jupiters for the nebular theory of solar system formation? A) It has been discarded. B) It has been modified to allow for the formation of gas giants within the frost line. C) It has been modified to allow for planets to migrate inwards or outwards due to gravitational interactions. D) Its status is unclear and awaits further observations that will determine whether hot Jupiters are dense Earth like planets or gas giants. E) It remains unchanged as it only needs to explain our Solar System.

C

Which of the following is a consequence of the discovery of hot Jupiters for understanding our own Solar System? A) It shows that our Solar System is very unusual. B) It shows that our Solar System is very typical. C) It shows that we do not fully understand the formation of our Solar System. D) It shows that life in the Universe is rare. E) It shows that Jupiter is unusually cold.

C

Which of the following is most unlikely to be found on Titan? A) lakes of liquid methane or ethane B) rain or snow consisting of methane or ethane droplets or ice crystals C) lakes of liquid water in the warmer equatorial regions D) volcanic outgassing of methane and other gases

C

Which of the following is not a general characteristic of the four jovian planets in our solar system? A) They lack solid surfaces. B) They are composed mainly of hydrogen, helium, and hydrogen compounds. C) They are higher in average density than are the terrestrial planets. D) They are much more massive then any of the terrestrial planets.

C

Which of the following is the underlying reason why Venus has so little wind erosion? A) its small size B) its thick atmosphere C) its slow rotation D) its relatively close distance to the Sun

C

Which of the following methods has led to the most discoveries of massive planets orbiting near their parent stars? A) detecting the starlight reflected off the planet B) detecting the infrared light emitted by the planet C) detecting the gravitational effect of an orbiting planet by looking for the Doppler shifts in the star's spectrum D) detecting the shift of the star's position against the sky due to the planet's gravitational pull E) detecting a planet ejected from a binary star system

C

Which of the following most likely explains why Venus does not have a global magnetic field like Earth? A) It does not have a metallic core. B) Unlike Earth, Venus does not have a liquid outer core. C) Its rotation is too slow. D) It has too thick of an atmosphere.

C

Which of the following regions was the result of plumes of hot mantle rising in a hot spot within a plate? A) Alaska's Aleutian Islands B) Japan and the Philippines C) the islands of Hawaii D) the volcano Mount St. Helens E) all of the above

C

Which planet search technique is currently best suited to finding Earth-like planets? A) Doppler B) astrometric C) transit D) gravitational lensing E) combining all the above

C

Which previously unknown planet's location was predicted from mathematical calculations of orbital motions? A) Mercury B) Uranus C) Neptune D) Pluto E) all of the above

C

Why are Saturn's rings so thin? A) Saturn's gravity prevents particles from migrating upwards out of the rings. B) The "gap" moons shepherd the particles and maintain its thin profile. C) Any particle in the ring with an orbital tilt would collide with other ring particles, flattening its orbit. D) Solar radiation pressure keeps particles pressed into the rings. E) The current thinness is a short-lived phenomenon that is special to this time.

C

Why are many of the newly detected extrasolar planets called "hot Jupiters"? A) Their masses and composition are similar to what we would expect if Jupiter were hotter. B) The planets tend to be detected around more massive, hotter stars than our Sun. C) Their masses are similar to Jupiter but they are very close to the central star and therefore hot. D) Their masses are similar to Jupiter but their composition is similar to Mercury. E) The discovery of other planets is very exciting.

C

Why are the inner planets made of denser materials than the outer planets? A) The Sun's gravity pulled denser materials toward the inner part of the solar nebula, while lighter gases escaped more easily. B) Denser materials were heavier and sank to the center of the nebula. C) In the inner part of the nebula only metals and rocks were able to condense because of the high temperatures, whereas hydrogen compounds, although more abundant, were only able to condense in the cooler outer regions. D) When the solar nebula formed a disk, materials naturally segregated into bands, and in our particular solar system the denser materials settled nearer the Sun while lighter materials are found in the outer part. E) In the beginning, when the protoplanetary disk was spinning faster, centrifugal forces flung the lighter materials toward the outer parts of the solar nebula.

C

Why are there no impact craters on the surface of Io? A) It is too small to have been bombarded by planetesimals in the early solar system. B) Jupiter's strong gravity attracted the planetesimals more strongly than Io and thus none landed on its surface. C) Io did have impact craters but they have all been buried in lava flows. D) Any craters that existed have been eroded through the strong winds on Io's surface. E) Io's thick atmosphere obscures the view of the craters.

C

Why do jovian planets bulge around the equator, that is, have a "squashed" appearance? A) They are much more massive than the terrestrial planets. B) Their large systems of moons and rings gravitationally attract the mass around the equator more. C) Their rapid rotation flings the mass near the equator outward. D) Their internal heat sources exert a pressure against the sides of the planets. E) all of the above

C

Why do the jovian planet interiors differ? A) The more distant planets formed in a cooler region of the solar nebula and therefore contain a greater proportion of ices than the closer jovian planets. B) They differ due to giant impacts at the late stages of planet formation. C) Accretion took longer further from the Sun, so the more distant planets formed their cores later and captured less gas from the solar nebula than the closer jovian planets. D) The solar heating is less for the more distant planets than the closer planets. E) The more distant planets had longer to form than the closer planets, since the solar nebula lasted longer at greater distances from the Sun.

C

Why does Earth have the strongest magnetic field among the terrestrial worlds? A) It is the only one that has a metallic core. B) It rotates much faster than any other terrestrial world. C) It is the only one that has both a partially molten metallic core and reasonably rapid rotation. D) It is by far the largest terrestrial world. E) It is the most volcanically active world.

C

Why does the Moon have a layer of "powdery soil" on its surface? A) Recent, large impacts shattered lunar rock to make this soil. B) It is made by the same processes that make powdery sand on Earth. C) It is the result of countless tiny impacts by small particles striking the Moon. D) It exists because the Moon accreted from powdery material after a giant impact blasted Earth.

C

Why is Earth's continental crust lower in density than seafloor crust? A) Continental crust is made from a low-density volcanic rock called basalt. B) Continental crust comes from volcanoes while seafloor crust comes from geysers. C) Continental crust is made as the lowest-density seafloor crust melts and erupts to the surface near subduction zones. D) Continental crust comes from Earth's inner core while seafloor crust comes from the outer core.

C

Why is it so difficult to take pictures of extrasolar planets? A) Extrasolar planets give off light at different wavelengths than planets in our solar system. B) No telescope is powerful enough to detect the faint light from a distant planet. C) Their light is overwhelmed by the light from their star. D) Telescopes are too busy with other projects.

C

Which two geological processes appear to have been most important in shaping the present surface of Venus? A) impacts and volcanoes B) impacts and tectonics C) tectonics and erosion D) volcanoes and tectonics E) volcanoes and erosion

D

A planet is detected via the Doppler technique. The repeating pattern of the stellar motion tells us A) the planet's size. B) the planet's mass. C) the planet's density. D) the orbital period of the planet. E) the orbital eccentricity of the planet.

D

A planet is most likely to have tectonic activity if it has A) low surface gravity. B) high surface gravity. C) low internal temperature. D) high internal temperature. E) a dense atmosphere.

D

A terrestrial world's lithosphere is A) a thin layer of rock that lies between the mantle and crust. B) the interior region in which the planet's magnetic field is generated. C) a layer of hot, molten rock encompassing the core and part of the mantle. D) a layer of relatively strong, rigid rock, encompassing the crust and part of the mantle.

D

According to our present theory of solar system formation, which of the following best explains why the solar nebula ended up with a disk shape as it collapsed? A) It was fairly flat to begin with, and retained this flat shape as it collapsed. B) The force of gravity pulled the material downward into a flat disk. C) the law of conservation of energy D) It flattened as a natural consequence of collisions between particles in the nebula.

D

According to our theory of solar system formation, what are asteroids and comets? A) the shattered remains of collisions between planets B) chunks of rock or ice that condensed after the planets and moons finished forming C) chunks of rock or ice that were expelled from planets by volcanoes D) leftover planetesimals that never accreted into planets

D

According to our theory of solar system formation, which law best explains why the central regions of the solar nebula got hotter as the nebula shrank in size? A) the law of conservation of angular momentum B) Newton's third law C) the two laws of thermal radiation D) the law of conservation of energy

D

Based on all we know about the terrestrial worlds, what single factor appears to play the most important role in a terrestrial planet's geological destiny? A) its composition B) its distance from the Sun C) whether or not it has liquid water D) its size

D

By itself, the Doppler technique provides a measure of a planet's A) minimum mass. B) orbital radius. C) orbital eccentricity. D) all of the above

D

How are the orbits of extrasolar planets different from the orbits of planets in our solar system? A) Many extrasolar planets orbit their stars backward. B) Many extrasolar planets are on very tilted orbits compared to what we'd expect. C) Many extrasolar planets do not travel on elliptical orbits. D) Many extrasolar planets travel on very eccentric orbits.

D

How do astronomers think Saturn generates its internal heat? A) radioactive decay B) internal friction due to its high rotation rate C) chemical processes D) by raining dense helium droplets from higher to lower altitudes, resembling the process of differentiation E) nuclear fusion in the core

D

How do typical wind speeds in Jupiter's atmosphere compare to typical wind speeds on Earth? A) They are about the same as average winds on Earth. B) They are slightly faster than average winds on Earth. C) They are slightly slower than average winds on Earth. D) They are much faster than hurricane winds on Earth.

D

How does Jupiter's core compare to Earth's? A) It is the same size and mass. B) It is about 10 times larger both in size and mass. C) It is about 10 times larger in size and the same mass. D) It is about the same size but is 10 times more massive. E) Jupiter doesn't have a core-it is made entirely from hydrogen and helium.

D

How have we been able to construct detailed maps of surface features on Venus? A) by studying Venus from Earth with powerful telescopes B) by studying Venus with powerful optical telescopes on spacecraft that were sent to orbit Venus C) by making computer models of geological processes on Venus D) by using radar from spacecraft that were sent to orbit Venus E) by landing spacecraft on the surface for close-up study

D

How will the Kepler mission (scheduled for 2008 launch) look for planets around other stars? A) It will look for Doppler shifts in stellar spectra. B) It will be sufficiently powerful to take low-resolution photographs of planets orbiting nearby stars. C) It will look for slight back and forth shifts in a star's position in our sky. D) It will look for slight changes in a star's brightness that repeat at regular intervals.

D

Jupiter and the other jovian planets are sometimes called "gas giants." In what sense is this term misleading? A) The materials they are made of are not the kinds of thing we usually think of as gases. B) They are not in any sense "giants." C) Actually, it's a great description, because these worlds are big and gaseous throughout. D) They actually contain relatively little material in a gaseous state.

D

Overall, Jupiter's composition is most like that of A) Earth. B) a comet. C) an asteroid. D) the Sun.

D

Rank the five terrestrial worlds in order of size from smallest to largest. A) Mercury, Venus, Earth, Moon, Mars B) Mercury, Moon, Venus, Earth, Mars C) Moon, Mercury, Venus, Earth, Mars D) Moon, Mercury, Mars, Venus, Earth E) Mercury, Moon, Mars, Earth, Venus

D

Suppose a planet is discovered by the Doppler technique and is then discovered to have transits. In that case, we can determine all the following about the planet except A) its precise mass. B) its density. C) its physical size (radius). D) its rotation period. E) its orbital period

D

Suppose you are using the Doppler technique to look for planets around another star. What must you do? A) Compare many spectra of an orbiting planet taken over a period of many months or years. B) Compare the brightness of the star over a period of many months or years. C) Carefully examine a single spectrum of an orbiting planet. D) Compare many spectra of the star taken over a period of many months or years.

D

The Caloris Basin on Mercury covers a large region of the planet, but few smaller craters have formed on top of it. From this we conclude that A) erosion destroyed the smaller craters that formed on the basin. B) Mercury's atmosphere prevented smaller objects from hitting the surface. C) only very large impactors hit Mercury's surface in the past. D) the Caloris Basin formed toward the end of the solar system's period of heavy bombardment. E) the Caloris Basin was formed by a volcano.

D

The Doppler technique only provides a measure of the minimum mass of a planet because A) only a small part of the planet's motion is measured. B) without a transit observation, the size and therefore density of the planet is unknown. C) we do not know the exact composition of the planet. D) only the motion of star toward the observer is measured, not the full motion. E) we do not have the technology to make a direct image of a planet yet.

D

The Huygens probe took numerous pictures as it descended to Titan's surface in 2005. What did the pictures show? A) primitive life forms B) a densely cratered surface C) lava flows of molten basalt D) features or erosion, including what appeared to be dry river valleys and lakebeds

D

The age of our solar system is approximately A) 10,000 years. B) 3.8 million years. C) 4.5 million years. D) 4.6 billion years. E) 14 billion years.

D

The composition of a planet can be determined by A) the Doppler technique. B) astrometric measurements. C) transit observations. D) spectra. E) all of the above

D

The core, mantle, and crust of a planet are defined by differences in their A) geological activity. B) temperature. C) strength. D) composition. (density) E) color.

D

The fact that most moons always show the same face to their planet is A) very surprising and a great mystery. B) a natural consequence of the fact that the entire solar nebula rotated in the same direction. C) explained by the law of conservation of angular momentum. D) a natural consequence of tidal forces acting on the moons. E) a result of the fact that the moons once had atmospheres.

D

The first planets around other Sun-like stars were discovered A) by Huygens, following his realization that other stars are Suns. B) by Galileo following the invention of the telescope. C) at the turn of last century. D) about a decade ago. E) at the turn of this century.

D

Valles Marineris is a A) large valley on the Moon. B) vast plain on Mars. C) huge series of cliffs on Mercury. D) large canyon on Mars. E) large canyon on Venus.

D

What causes synchronous rotation? A) Most jovian moons were formed out of their planet's nebula with the same rotational period as their parent planet. B) Most jovian moons were formed out of their planet's nebula with the same orbital period. C) A massive planet exerts a tidal force on a moon that causes the moon to obtain the same rotational period as its parent planet. D) A massive planet exerts a tidal force on a moon that causes the moon to align itself such that its tidal bulges always point toward and away from the planet. E) orbital resonances with other moons

D

What do models suggest make up the clouds on "hot Jupiters"? A) ammonia B) methane C) water D) rock dust E) sodium

D

What is Jupiter's Great Red Spot? A) the place where reddish particles from Io impact Jupiter's surface B) a hurricane that comes and goes on Jupiter C) a large mountain peak poking up above the clouds D) a long-lived, high-pressure storm E) the place where Jupiter's aurora is most visible

D

What is the most important factor that determines the thickness, and therefore strength, of the lithosphere? A) pressure B) viscosity C) composition D) internal temperature E) distance of planet from Sun

D

What is the primary reason that astronomers suspect that some jovian moons were captured into their current orbits? A) Some moons have a composition that differs from the composition of the planets. B) Astronomers have observed moons being captured. C) Some moons are surprisingly large in size. D) Some moons have orbits that are "backwards" (compared to their planet's rotation) or highly inclined to their planet's equator.

D

What mechanism is most responsible for generating the internal heat of Io that drives the volcanic activity? A) accretion B) radioactive decay C) differentiation D) tidal heating E) bombardment

D

What observational evidence supports the idea that Mercury once shrank by some 20 kilometers in radius? A) the presence of many impact craters B) the characteristics of the Caloris Basin C) Mercury's unusually high density D) the presence of many long, tall cliffs

D

What percentage of the solar nebula's mass consisted of hydrogen and helium gases? A) 0.5 percent B) 5 percent C) 50 percent D) 98 percent E) 100 percent

D

Which detection techniques can find the planet's orbital distance (assuming we know the mass of the star)? A) only the Doppler technique B) only the transit technique C) only the astrometric technique D) all of these techniques

D

Which internal energy source produces heat by converting gravitational potential energy into thermal energy? A) accretion B) differentiation C) radioactivity D) both A and B E) all of the above

D

Which internal heat source still generates heat within the terrestrial worlds today? A) heat of accretion B) heat from differentiation C) heat from convection D) heat from radioactive decay

D

Which of the following best describes the geological histories of the Moon and Mercury? A) Impact cratering is the only major geological process that has affected their surfaces. B) All four geological processes were important in their early histories, but only impact cratering still reshapes their surfaces today. C) Impact cratering shaped these worlds early in their histories. Then, during the past few million years, they were reshaped by episodes of volcanism and tectonics. D) Early in their histories, they suffered many impacts and experienced some volcanism and tectonics, but they now have little geological activity at all.

D

Which of the following best describes the lunar maria? A) densely cratered regions on the Moon B) mountainous regions on the Moon C) frozen oceans of liquid water on the Moon D) relatively smooth, flat plains on the Moon

D

Which of the following best describes why the smaller terrestrial worlds have cooler interiors than the larger ones? A) They were cooler when they formed. B) The smaller ones are farther from the Sun. C) They have relatively fewer radioactive elements. D) They have relatively more surface area compared to their volumes. E) They had more volcanic eruptions in the past, which released their internal heat.

D

Which of the following describes erosion? A) the excavation of bowl-shaped depressions by asteroids or comets striking a planet's surface B) the eruption of molten rock from a planet's interior to its surface C) the disruption of a planet's surface by internal stresses D) the wearing down or building up of geological features by wind, water, ice, and other phenomena of planetary weather

D

Which of the following does not provide evidence that Mars once had abundant liquid water on its surface? A) the presence of features that look like dried up river beds B) the presence of "blueberries" made of the mineral hematite C) the presence of very old craters that appear to have been eroded by rain D) the presence of canali, discovered in the late 1800s by Giovanni Schiaparelli and mapped by Percival Lowell

D

Which of the following does not yield information on jovian planet interiors? A) Earth-based observations of the mass and size of the planets B) spacecraft measurements of magnetic and gravitational fields C) laboratory studies and theoretical models D) spectroscopy of the cloud layers E) detailed observations of planetary shapes

D

Which of the following has not been detected around other stars in the Galaxy? A) a collapsing nebula of gas B) flattened, spinning disks C) jovian planets D) terrestrial planets E) strong stellar winds

D

Which of the following is not a piece of evidence supporting the idea that Europa may have a subsurface ocean? A) Europa has a magnetic field that appears to be induced by Jupiter's magnetic field. B) Photos of Europa's surface show regions that appear to consist of jumbled icebergs frozen in place. C) Europa's surface shows very few impact craters. D) Astronomers have detected small lakes of liquid water on Europa's surface.

D

Which of the following is not evidence for plate tectonics on Earth? A) some continental boundaries fit together like pieces of a jigsaw puzzle B) similar rocks and fossils are found in different continents C) high ocean ridges between the continents D) existence of volcanoes E) earthquakes

D

Which of the following is the origin of almost all the large moons around the jovian planets? A) They are captured asteroids. B) They are captured comets. C) They are captured planets. D) They were formed by condensation and accretion in a disk of gas around the planet. E) They were formed by giant impacts.

D

Which of the following places is the result of volcanoes erupting over a hot spot in the mantle? A) the Himalayas B) the Appalachians C) California D) Hawaii

D

Which of the following show evidence of ancient river beds? A) the Moon B) Mercury C) Venus D) Mars E) all of the above

D

Which of the following statements about the moons of the jovian planets is not true? A) Some of the moons are big enough that we'd call them planets (or dwarf planets) if they orbited the Sun. B) One of the moons has a thick atmosphere. C) Many of the moons are made largely of ices. D) Most of the moons are large enough to be spherical in shape, but a few have the more potato-like shapes of asteroids.

D

Which of the following statements about the rings of the four jovian planets is not true? A) All rings lie within their planet's Roche zone. B) All the particle orbits are fairly circular, near their planet's equatorial plane. C) All have gaps and ringlets, probably due to gap moons, shepherd moons, and orbital resonances. D) All probably look much like they did when the solar system first formed. E) All are made of individual particles of rock or ice that orbit in accord with Kepler's laws: inner ring particles orbiting faster, and outer ring particles orbiting slower

D

Which of the following types of material can condense into what we call ice at low temperatures? A) hydrogen and helium B) rock C) metal D) hydrogen compounds

D

Which planet may have helium rain in its interior, and what does this rain do? A) Uranus, where it makes the ground wet. B) Neptune, where it is restructuring the planet's interior. C) Jupiter, where it may be an energy source for the Great Red Spot. D) Saturn, where it generates heat as it falls downward.

D

Which statement about Saturn's rings is not true? A) The large gap known as the Cassini Division is shaped by an orbital resonance with the moon Mimas, which orbits well outside the rings. B) Some features of the rings are shaped by small moons that actually orbit within the ring system. C) The rings are so thin that they essentially disappear from view when seen edge-on. D) The rings must look much the same today as they did shortly after Saturn formed.

D

Which statement about planetary rings is not true? A) All four jovian planets have rings. B) Individual ring particles orbit their planet in accord with Kepler's laws, so that particles closer in orbit faster than particles farther out. C) Rings are always located closer to a planet's surface than any large moons. D) Saturn's rings formed along with its moons 4.6 billion years ago.

D

Which two factors are most important to the existence of plate tectonics on Earth? A) oxygen in the atmosphere and mantle convection B) the existence of life and oxygen in the atmosphere C) Earth's liquid outer core and solid inner core D) mantle convection and a thin lithosphere

D

Why did the solar nebula flatten into a disk? A) The interstellar cloud from which the solar nebula formed was originally somewhat flat. B) The force of gravity from the Sun pulled the material downward into a flat disk. C) As the nebula cooled, the gas and dust settled onto a disk. D) It flattened as a natural consequence of collisions between particles in the spinning nebula, changing random motions into more orderly ones. E) The force of gravity from the planets pulled the material downward into a flat disk.

D

Why is the radiation so intense in the region that traces Io's orbit around Jupiter (the Io torus)? A) Io's gravity allows this region to capture huge numbers of charged particles from the solar wind. B) An orbital resonance between Io, Europa, and Ganymede makes the radiation intense. C) Jupiter's strong magnetic field makes the radiation intense everywhere, and the region around Io is no different than any other region. D) The region is full of gases that become ionized after they are released from volcanoes on Io.

D

You discover an impact crater that is 10 kilometers across. Which of the following can you conclude? A) It was created by the impact of an object about 10 kilometers across. B) It was created within the past 10 million years. C) It was created within the past 1 billion years. D) It was created by the impact of an object about 1 kilometer across.

D

what are the conditions necessary for a terrestrial planet to have a strong magnetic field? A) a molten metallic core only B) fast rotation only C) a rocky mantle only D) both a molten metallic core and reasonably fast rotation E) both a metal core and a rocky mantle

D

Planetary rings are A) nearer to their planet than any of the planet's large moons. B) orbiting in the equatorial plane of their planet. C) composed of a large number of individual particles that orbit their planet in accord with Kepler's third law. D) known to exist for all of the jovian planets. E) all of the above

E

Some of the oldest continental crust on Earth lies in A) Hawaii. B) California. C) the Great Plains. D) the deep South. E) Northeastern Canada.

E

A planet is detected via the Doppler technique. The shape of the periodic velocity pattern tells us A) the planet's size. B) the planet's mass. C) the planet's density. D) the orbital period of the planet. E) the orbital eccentricity of the planet.

E

How do astronomers think Jupiter generates its internal heat? A) radioactive decay B) internal friction due to its high rotation rate C) chemical processes D) nuclear fusion in the core E) by contracting, changing gravitational potential energy into thermal energy

E

How many more times is the atmospheric pressure in Jupiter's core greater than the atmospheric pressure at Earth's surface? A) 10 thousand B) 100 thousand C) 1 million D) 10 million E) 100 million

E

How much brighter is a Sun-like star than the reflected light from a planet orbiting around it? A) a hundred times brighter B) a thousand times brighter C) ten thousand times brighter D) a million times brighter E) a billion times brighter

E

How thick are Saturn's rings from top to bottom? A) a few million kilometers B) a few tens of thousands of kilometers C) a few hundred kilometers D) a few kilometers E) a few tens of meters

E

Under what circumstances can differentiation occur in a planet? A) The planet must have a rocky surface. B) The planet must be made of both metal and rock. C) The planet must have an atmosphere. D) The planet must be geologically active, that is, have volcanoes, planet quakes, and erosion from weather. E) The planet must have a molten interior.

E

What are the circumstances under which convection can occur in a substance? A) when the substance is subjected to a strong magnetic field B) when dense material is being added to the substance C) when the substance is strongly shaken or disturbed by a strong wind D) when the substance is strongly cooled from underneath E) when the substance is strongly heated from underneath

E

What kind of surface features may result from tectonics? A) mountains B) valleys C) volcanos D) cliffs E) all of the above

E

When we see a region of a planet that is not as heavily cratered as other regions, we conclude that A) there is little volcanic activity to create craters. B) the planet is rotating very slowly and only one side was hit by impactors. C) the planet formed after the age of bombardment and missed out on getting hit by leftover planetesimals. D) the surface in the region is older than the surface in more heavily cratered regions. E) the surface in the region is younger than the surface in more heavily cratered regions.

E

Which of the following are relatively unchanged fragments from the early period of planet building in the solar system? A) the moons of Mars B) asteroids C) Kuiper belt comets D) Oort cloud comets E) all of the above

E

Which of the following does not have a major effect in shaping planetary surfaces? A) impact cratering B) volcanism C) tectonics D) erosion E) magnetism

E

Which of the following is not due to tidal forces? A) the synchronous rotation of the Moon around Earth B) the volcanos on Io (a moon of Jupiter) C) the rings of Saturn D) the grooved terrain of Enceladus (a moon of Saturn) E) the backward orbit of Triton (a moon of Neptune)

E

Which of the following planets cannot be seen with the naked eye? A) Venus B) Mars C) Jupiter D) Saturn E) Neptune

E

Which of the following statements about Titan is not true? A) It may have an ocean of liquid ethane. B) Its atmosphere is mostly nitrogen. C) Its temperature is too cold for liquid water to exist. D) Its surface is hidden from view by its thick atmosphere. E) It is the coldest moon in the solar system.

E

Which of the following worlds have the thinnest lithospheres? A) Earth and the Moon B) Venus and the Moon C) Mercury and Venus D) Earth and Mars E) Earth and Venus

E

Which of the jovian planets have rings? A) Jupiter B) Saturn C) Uranus D) Neptune E) all of the above

E

Which two properties are most important in determining the surface temperature of a planet? A) composition and distance from the Sun B) size and chemical composition C) size and atmosphere D) internal temperature and atmosphere E) distance from the Sun and atmosphere

E

Why does the Moon have a layer of powdery "soil" on its surface? A) Large impacts shattered lunar rock to make this soil. B) The soil exists because the Moon accreted from powdery material after a giant impact blasted Earth. C) Volatiles escaping from the Moon's interior bubble upward and make the soil. D) The soil is the result of the same processes that make powdery sand on Earth. E) It's the result of gradual erosion by micrometeorites striking the Moon.

E

The density of a planet can be determined by combining Doppler and astrometric measurements.

False

The magnetic and rotational north poles on Earth are the same.

False

There is no erosion of surface features on the Moon.

False

Uranus continues to generate internal heat through gravitational contraction.

False

All the planets in the solar system rotate in the same direction as they orbit the Sun.

False

Because we have not found another planetary system like our own, we can conclude that our Solar System must be quite unusual.

False

Earth is the only terrestrial planet to have experienced tectonic stresses and volcanic activity.

False

Erosion is the most important geological process on Venus.

False

If Jupiter were 10 times more massive, it would generate nuclear fusion in its core and be a star instead of a planet.

False

Impacts were extremely common in the young solar system but no longer occur today.

False

In the inner solar system, the largest surface features are found on the largest planets.

False

Jupiter's Great Red Spot is a low-pressure storm like a hurricane on Earth.

False

Nebular theory predicts that other solar systems that formed in the same way should also have 8 planets.

False

Once a planet forms in a disk-like nebula around a star, its orbit is fixed and will never change.

False

Pluto exerts a noticeable gravitational influence on Uranus.

False

Process of Science: We cannot test the nebular theory for the formation of the Solar System in a rigorous scientific way because the Sun and planets formed in the distant past.

False

Smaller worlds generally have thinner lithospheres.

False

A planet's size can be determined by observing its transit across a star.

True