ASTR101 Solar System Astronomy Practice Final, Astronomy 101 Final Study Guide

The Huygens probe took numerous pictures as it descended to Titan's surface in 2005. What did the pictures show?

features or erosion, including what appeared to be dry river valleys and lakebeds

The orbital resonance also gives Europa an elliptical orbit, so it also experiences tidal heating. However, Europa experiences less tidal heating than Io, because Europa __________ than Io. A) Contains much more ice B) Is more perfectly spherical in shape C) Is much smaller D) Is farther from Jupiter

D) Is farther from Jupiter

How might Triton's capture be relevant to its geological activity?

Even though Triton is much smaller than our Moon, Triton' surface shows evidence of relatively recent geological activity. This can be because of the tidal heating that occurred when the moon was captured.

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) Liquid core of hydrogen compounds; liquid hydrogen layer; metallic hydrogen layer; gaseous hydrogen layer; cloud layer D) Solid rock core; layer of solid metallic hydrogen; layer of pure liquid hydrogen; cloud layer

A) Core of rock, metal, and hydrogen compounds; thick layer of metallic hydrogen; layer of liquid hydrogen; layer of gaseous hydrogen; cloud layer

Which of the following best explains why Jupiter's density is higher than Saturn's? A) Jupiter is more massive than Saturn. B) Jupiter is closer to the Sun than Saturn. C) Jupiter has a higher proportion of hydrogen compounds and rock than Saturn. D) Jupiter has a stronger magnetic field than Saturn.

A) Jupiter is more massive than Saturn.

Which of the following statements best explains why the densities of Uranus and Neptune are higher than those of Jupiter and Saturn? A) They have a higher proportion of hydrogen compounds and rock. B) They have higher masses. C) Their interiors are more compressed due to stronger gravity. D) They are at greater distances from the Sun. E) They have stronger magnetic fields.

A) They have a higher proportion of hydrogen compounds and rock.

We cannot see tidal forces or tidal heating; rather, we predict that they must occur based on the orbital characteristics of the moons. What observational evidence confirms that tidal heating is important on Io?

Active volcanoes on Io

How do the jovian planet interiors differ?

All have cores of about the same mass, but differ in the amount of surrounding hydrogen and helium.

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) 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) Countless icy particles, ranging in size from dust grains to large boulders C) A solid, shiny surface, looking much like a piece of a DVD but a lot bigger D) Dozens of large "moonlets" made of metal and rock, each a few kilometers across

B) Countless icy particles, ranging in size from dust grains to large boulders

From Part A, Io's elliptical orbit is necessary to its tidal heating. This elliptical orbit, in turn, is a result of the orbital resonance among Io, Europa, and Ganymede. This orbital resonance causes Io to have a more elliptical orbit than it would otherwise, because __________. A) All three moons orbit with the same period, staying aligned at all times B) Lo periodically passes Europa and Ganymede in the same orbital position C) Europa and Ganymede are unusually large moons D) Europa and Ganymede always pull on Io from the same direction as Jupiter pulls on Io

B) Lo periodically passes Europa and Ganymede in the same orbital position

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

B) They are much faster than hurricane winds on Earth.

We now know of many Jupiter-size planets around other stars. Suppose that future observations show that one of these planets has two orbiting moons. What additional information, if any, would we need to decide whether these moons experience tidal heating? A) We need to know whether the planet also has a third moon. B) We need to know their orbital periods. C) We need to know whether either moon is volcanically active. D) No other information is needed: With two moons, there is sure to be tidal heating. E) No other information is needed: With two moons, there is no chance of any tidal heating.

B) We need to know their orbital periods.

We cannot see tidal forces or tidal heating; rather, we predict that they must occur based on the orbital characteristics of the moons. What observational evidence confirms that tidal heating is important on Io? A) Lo's unusual, egg-like shape B) The orbital resonance between Io, Europa, and Ganymede C) Active volcanoes on Io D) Lo's surprisingly elliptical orbit

C) Active volcanoes on Io

Saturn's rings... A) Have looked basically the same since they formed along with Saturn. B) Were created long ago when tidal forces tore apart a large moon. C) Are continually supplied by impacts with small moons.

C) Are continually supplied by impacts with small moons.

Based on the leading scientific theory of solar system formation, which of the following statements best explains why Uranus and Neptune have a significantly different composition and higher density than Jupiter and Saturn? A) The lower masses of Uranus and Neptune allowed more of their hydrogen and helium gas to escape into space. B) The lower temperatures at the locations of Uranus and Neptune allowed more material to condense into solid form into solid form. C) Jupiter and Saturn captured more gas from the solar nebula than Uranus and Neptune. D) Jupiter and Saturn formed closer to the Sun, where there was more hydrogen and helium gas and less hydrogen compounds and rock.

C) Jupiter and Saturn captured more gas from the solar nebula than Uranus and Neptune.

Which lists the jovian planets in order of increasing distance from the Sun? A) Jupiter, Saturn, Uranus, Pluto B) Saturn, Jupiter, Uranus, Neptune C) Jupiter, Saturn, Uranus, Neptune

C) Jupiter, Saturn, Uranus, Neptune

Lo experiences tidal heating primarily because __________. A) Lo has an unusually elongated shape that makes it look more like an egg than a sphere B) Lo is made of relatively soft materials that deform quite easily C) Lo's elliptical orbit causes the tidal force on Io to vary as it orbits Jupiter D) Lo is located very close to Jupiter

C) Lo's elliptical orbit causes the tidal force on Io to vary as it orbits Jupiter

Which of the following is a general characteristic of the four jovian planets in our solar system? A) They have very little hydrogen, helium, and hydrogen compounds. B) They have solid surfaces. C) They are lower in average density than are the terrestrial planets. D) They are less massive than any of the terrestrial planets.

C) They are lower in average density than are the terrestrial planets.

Which of the following statements best describes the general pattern of composition among the four jovian planets? A) Jupiter is made mostly of hydrogen, Saturn is made mostly of helium, Uranus is made mostly of hydrogen compounds, and Neptune is made mostly of rock. B) Jupiter is made mostly of hydrogen and helium, while the other three jovian planets are made mostly of hydrogen compounds. C) All four planets have essentially the same composition. D) Jupiter and Saturn have compositions that are fairly different from the compositions of Uranus and Neptune.

D) Jupiter and Saturn have compositions that are fairly different from the compositions of Uranus and Neptune.

Look at the densities of the jovian planets given in Figure 1. Which of the following statements best describes the pattern of jovian planet densities? A) The more massive the planet, the higher the density. B) Jupiter is the densest, and the densities of the other planets decrease in order of distance from the Sun. C) Jupiter is the densest, and the densities of the other planets increase in order of distance from the Sun. D) There is no clear trend in the densities. E) The more massive the planet, the lower the density.

D) There is no clear trend in the densities.

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?

Ice has a lower melting point than rock.

As you learned in Part A, Io's elliptical orbit is necessary to its tidal heating. This elliptical orbit, in turn, is a result of the orbital resonance among Io, Europa, and Ganymede. This orbital resonance causes Io to have a more elliptical orbit than it would otherwise, because __________.

Io periodically passes Europa and Ganymede in the same orbital position.

Io experiences tidal heating primarily because __________.

Io's elliptical orbit causes the tidal force on Io to vary as it orbits Jupiter.

How does Jupiter's core compare to Earth?

It is about the same size but is 10 times more massive.

Why do we think Triton is a captured moon?

It orbits Neptune in the direction opposite to Neptune's rotation. | It orbits Neptune at a high inclination to Neptune's equator.

Why do astronomers think Miranda has such an unusual surface?

It underwent an episode of tidal heating in the past

Based on the leading scientific theory of solar system formation, which of the following statements best explains why Uranus and Neptune have a significantly different composition than Jupiter and Saturn?

Jupiter and Saturn captured more gas from the solar nebula than Uranus and Neptune.

Which of the following statements best describes the general pattern of composition among the four jovian planets?

Jupiter and Saturn have compositions that are fairly different from the compositions of Uranus and Neptune.

Which of the following best explains why Jupiter's density is higher than Saturn's?

Jupiter is more massive than Saturn

Why is Saturn almost as big as Jupiter, despite its smaller mass?

Jupiter's greater mass compresses it more, thus increasing its density.

Why do Uranus and Neptune have blue methane clouds but Jupiter and Saturn do not?

Methane does not condense into ice in the warmer atmospheric temperatures of Jupiter and Saturn.

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

a) Its density would increase but its diameter would barely change.

Why is Jupiter denser than Saturn?

The extra mass of Jupiter compresses its interior to a greater extent than that of Saturn

Why do jovian planets bulge around the equator, that is, have a "squashed" appearance?

Their rapid rotation flings the mass near the equator outward.

Look at the average densities of the jovian planets given in Figure 1. Can you identify a trend in jovian planet densities with mass or distance from the Sun?

There is no clear trend in the densities with mass or distance.

Look at the densities of the jovian planets given in Figure 1. Which of the following statements best describes the pattern of jovian planet densities?

There is no clear trend in the densities.

How do typical wind speeds in Jupiter's atmosphere compare to typical wind speeds on Earth?

They are much faster than hurricane winds on Earth

Which of the following statements best explains why the densities of Uranus and Neptune are higher than that of Saturn, even though Saturn is much more massive?

They have a higher proportion of hydrogen compounds and rock.

Which of the following statements best explains why the densities of Uranus and Neptune are higher than those of Jupiter and Saturn?

They have a higher proportion of hydrogen compounds and rock.

49. What's the fundamental reason that Mars, unlike the Earth, has become virtually geologically dead? a) its small size compared to Earth b) its slow rotation compared to the Earth c) its closer distance than Earth to the Sun d) its large size compared to the Earth e) its rapid rotation compared to the Earth f) its farther distance than Earth to the Sun

a) its small size compared to Earth

Which of the following statements best describes the general pattern of composition among the four jovian planets?

Uranus and Neptune contain relatively more rock and hydrogen compounds than Jupiter and Saturn.

We now know of many Jupiter-size planets around other stars. Suppose that future observations show that one of these planets has two orbiting moons. What additional information, if any, would we need to decide whether these moons experience tidal heating?

We need to know their orbital periods

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

a) Continental crust is made as the lowest-density seafloor crust melts and erupts to the surface near subduction zones.

32. What would happen to Earth if we somehow moved our planet to the orbit of Venus? a) Earth would suffer a runaway greenhouse effect and become as hot or hotter than Venus. b) Temperatures would rise only slightly, but enough to melt the polar caps. c) The fact that we have oceans would moderate the temperature change due to moving our planet, so temperature would hardly change at all. d) Being so much closer to the Sun would almost immediately cause the surface of Earth to melt, and all our cities would then be destroyed by the hot lava.

a) Earth would suffer a runaway greenhouse effect and become as hot or hotter than Venus.

14. When is the soonest we are likely to have images and spectra of Earthlike planets around other stars? a) In a decade or two, through space missions now in the early planning stages. b) Any day now, thanks to new, large, ground-based telescopes. c) In just a few years, through the Kepler mission. d) We already have images and spectra of Earthlike planets around other stars.

a) In a decade or two, through space missions now in the early planning stages.

21. Suppose we discover a new comet on an orbit that brings it closer to the Sun than Mercury every 125 years. What can we conclude? a) It has been on its current orbit for only a very short time compared to the age of our solar system. b) It came from the Oort cloud. c) It has a coma and tail during most of each orbit. d) It came from the Kuiper belt.

a) It has been on its current orbit for only a very short time compared to the age of our solar system.

31. Does Venus have auroras around its poles, like the Earth? Why or why not? a) No, because it lacks a global magnetic field. b) Yes, because strong winds generate light near its poles. c) Yes, because it is bombarded by charged particles from the Sun. d) No, because its atmosphere is too thick.

a) No, because it lacks a global magnetic field.

13. According to current science, why didn't oxygen begin to accumulate in the atmosphere for more than a billion years after life appeared on the Earth? a) Oxygen released by life was removed from the atmosphere by chemical reactions with surface rocks until the surface rock could absorb no more. b) Oxygen released by life was removed from the atmosphere by dissolving in the ocean until the oceans could dissolve no more. c) Early life did not release oxygen, and oxygen releasing organisms didn't evolve for a billion years after the earliest life. d) Early forms of animal life consumed the oxygen released by plants during the first billion years of life on Earth.

a) Oxygen released by life was removed from the atmosphere by chemical reactions with surface rocks until the surface rock could absorb no more.

9. Deuterium is much more abundant on Venus than Earth. What do we think this fact tells us about Venus? a) That it has lost a tremendous amount of water as a result of molecules being split by ultraviolet light and the hydrogen escaping to space. b) That the greenhouse effect on Venus must have been much weaker in the distant past. c) That volcanoes on Venus did not outgas as much water as volcanoes on Earth. d) That it once had a much stronger magnetic field than it does today.

a) That it has lost a tremendous amount of water as a result of molecules being split by ultraviolet light and the hydrogen escaping to space.

28. 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) a massive planet that is close to its star

33. 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 rotation period b) its orbital period c) its physical size (radius) d) its precise mass e) its density

a) its rotation period

3. What are the two geological features that appear to set Earth apart from all the other terrestrial worlds? a) plate tectonics and widespread erosion b) mantle convection and a thick atmosphere c) shield volcanoes and plate tectonics d) significant volcanism and tectonics

a) plate tectonics and widespread erosion

36. In science fiction movies, spaceships are often shown dodging through large numbers of closely spaced, boulder-size objects. Which of the following real things in our solar system would look most like such science fiction dangers? a) the rings of Saturn b) the atmosphere of Jupiter c) the asteroid belt d) the Oort cloud

a) the rings of Saturn

The belts and zones of Jupiter are

alternating bands of rising and falling air at different latitudes.

17. Which of the following best describes the geological histories of the Moon and Mercury? a) 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. b) Early in their histories, they suffered many impacts and experienced some volcanism and tectonics, but they now have little geological activity at all. c) Impact cratering is the only major geological process that has affected their surfaces. d) All four geological processes were important in their early histories, but only impact cratering still reshapes their surfaces today.

b) Early in their histories, they suffered many impacts and experienced some volcanism and tectonics, but they now have little geological activity at all.

26. Why does Earth have so little carbon dioxide in its atmosphere compared to Venus? a) Earth once had a lot of carbon dioxide, but it was lost to space during the heavy bombardment early in our solar system's history. b) Earth has just as much carbon dioxide as Venus, but most of it is locked up in carbonate rocks rather than being free in the atmosphere. c) Earth's volcanoes outgassed far less carbon dioxide than those on Venus. d) Chemical reactions turned Earth's carbon dioxide into nitrogen.

b) Earth has just as much carbon dioxide as Venus, but most of it is locked up in carbonate rocks rather than being free in the atmosphere.

10. All the following statements about Mars are true. Which one might have led to a significant loss of atmospheric gas to space? a) Outgassed water molecules are split apart, and the oxygen then reacts chemically with surface rock on Mars. b) Mars lost any global magnetic field that it may once have had. c) Mars probably once had a much higher density of greenhouse gases in its atmosphere than it does today. d) The axis tilt of Mars is thought to change significantly with time.

b) Mars lost any global magnetic field that it may once have had.

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

b) Only a tiny percentage of stars are surrounded by spinning disks of gas during their formation.

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

b) Some moons have orbits that are "backwards" (compared to their planet's rotation) or highly inclined to their planet's equator.

22. How can we best observe the Sun's chromosphere and corona? a) The chromosphere is best observed with infrared telescopes and the corona is best observed with ultraviolet telescopes. b) The chromosphere is best observed with ultraviolet telescopes and the corona is best observed with X-ray telescopes. c) The chromosphere and corona are both best studied with radio telescopes. d) The chromosphere and corona are both best studied with visible light.

b) The chromosphere is best observed with ultraviolet telescopes and the corona is best observed with X-ray telescopes.

8. 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) The region is full of gases that become ionized after they are released from volcanoes on Io. c) An orbital resonance between Io, Europa, and Ganymede makes the radiation intense. d) Jupiter's strong magnetic field makes the radiation intense everywhere, and the region around Io is no different than any other region.

b) The region is full of gases that become ionized after they are released from volcanoes on Io.

6. Suppose that Earth's ice caps melted, but everything else about the Earth's surface and atmosphere stayed the same. What would happen to Earth's average surface temperature? a) The surface temperature would decrease. b) The surface temperature would increase. c) The temperature would not be affected at all. d) The surface temperature would change radically, until it was equal to the melting temperature of ice.

b) The surface temperature would increase.

40. 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 locations of various materials in the solar nebula. b) The temperatures at which various materials will condense from gaseous form to solid form. c) The atomic mass numbers of various materials. d) The amounts of energy required to ionize various materials.

b) The temperatures at which various materials will condense from gaseous form to solid form.

44. Why do sunspots appear dark in pictures of the Sun? a) They are holes in the solar surface through which we can see through to deeper, darker layers of the Sun. b) They actually are fairly bright, but appear dark against the even brighter background of the surrounding photosphere. c) They are extremely hot and emit all their radiation as X rays rather than visible light. d) They are too cold to emit any visible light.

b) They actually are fairly bright, but appear dark against the even brighter background of the surrounding photosphere.

30. Why do astronomers believe that Triton is a captured moon? a) Triton appears to be made mostly of ice. b) Triton orbits Neptune in a direction opposite that of Neptune's rotation. 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 is very small and potato-shaped, which is common of captured moons.

b) Triton orbits Neptune in a direction opposite that of Neptune's rotation.

47. Earth has been gradually warming over the past few decades. Based on a great deal of evidence, scientists believe that this warming is caused by _____. a) the fact that our politicians spout a lot of hot air b) human activities that are increasing the concentration of greenhouse gases in Earth's atmosphere c) the human release of chemicals called CFCs into the stratosphere d) the increase in forest fires during recent years

b) human activities that are increasing the concentration of greenhouse gases in Earth's atmosphere

15. 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) density similar to or lower than Jupiter's d) clouds made of rock dust

b) intense volcanism

42. Which two factors are most important to the existence of plate tectonics on Earth? a) the existence of life and oxygen in the atmosphere b) mantle convection and a thin lithosphere c) Earth's liquid outer core and solid inner core d) oxygen in the atmosphere and mantle convection

b) mantle convection and a thin lithosphere

23. Gaps in the asteroid belt (often called Kirkwood gaps) are caused by ______. a) tidal forces from Jupiter b) orbital resonances with Jupiter c) tidal forces from the Sun d) the competing gravitational tugs of Mars and Jupiter

b) orbital resonances with Jupiter

How do astronomers think Jupiter generates its internal heat?

by contracting, changing gravitational potential energy into thermal energy

How do astronomers think Saturn generates its internal heat?

by raining dense helium droplets from higher to lower altitudes, resembling the process of differentiation

45. How can we determine the reflectivity of an asteroid? a) By taking a photograph of it. b) By measuring its mass and radius. c) By comparing its brightness in visible light to its brightness in infrared light. d) By where it is located in the asteroid belt.

c) By comparing its brightness in visible light to its brightness in infrared light.

41. Which of the following is not a piece of evidence supporting the idea that an impact caused the mass extinction that occurred 65 million years ago? a) Grains of quartz formed under high pressure are found in a layer of clay that dates to 65 million years ago. b) Unusually large abundances of iridium and other rare metals are found in a layer of clay that dates to 65 million years ago. c) Fossilized dinosaur bones contain fragments of rock from the impact. d) A large impact crater along the coast of Mexico dates to 65 million years ago.

c) Fossilized dinosaur bones contain fragments of rock from the impact.

20. What is Pluto's moon Charon thought to have in common with our own Moon? a) It has the same basic composition. b) It has the same approximate mass. c) It probably formed as a result of a giant impact. d) It has the same average density.

c) It probably formed as a result of a giant impact.

39. Which of the following best explains why nuclear fusion requires bringing nuclei extremely close together? a) Fusion can proceed only by the proton-proton chain, and therefore requires that protons come close enough together to be linked up into a chain. b) Nuclei have to be very hot in order to fuse, and the only way to get them hot is to bring them close together. c) Nuclei normally repel because they are all positively charged and can be made to stick only when brought close enough for the strong force to take hold. d) Nuclei are attracted to each other by the electromagnetic force, but this force is only strong enough to make nuclei stick when they are very close together.

c) Nuclei normally repel because they are all positively charged and can be made to stick only when brought close enough for the strong force to take hold.

4. Why won't Pluto collide with Neptune? a) Pluto is always much farther from the Sun than Neptune. b) Actually, a collision of the two is inevitable within the next billion years. c) Pluto orbits the Sun exactly 2 times for every 3 Neptune orbits, which ensures they never come close together. d) Pluto's orbit never comes anywhere close to Neptune's orbit.

c) Pluto orbits the Sun exactly 2 times for every 3 Neptune orbits, which ensures they never come close together.

5. 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 Venus. Distance from Sun: same as Mars. Rotation rate: once every 25 hours. b) Size: same as Mars. Distance from Sun: same as Earth. Rotation rate: once every 18 hours. c) Size: twice as big as Earth. Distance from Sun: same as Mercury. Rotation rate: once every 6 months. d) Size: same as the Moon. Distance from Sun: same as Mars. Rotation rate: once every 10 days.

c) Size: twice as big as Earth. Distance from Sun: same as Mercury. Rotation rate: once every 6 months.

29. If the Sun's core suddenly shrank a little bit, what would happen in the Sun? a) The density of the core would decrease, causing the core to cool off and expand. b) The core would heat up, causing it to radiate so much energy that it would shrink even more. c) The core would heat up, fusion rates would increase, the core would re-expand. d) The core would cool off and continue to shrink as its density increased.

c) The core would heat up, fusion rates would increase, the core would re-expand.

48. 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) The water was brought to the forming Earth by planetesimals that accreted beyond the orbit of Mars.

37. 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) Gravity was too weak to allow asteroids to form in this part of the solar system. b) All the asteroids that formed between Mercury and Mars later migrated to the asteroid belt between Mars and Jupiter. c) 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. d) It was too hot for asteroids to form in this part of the solar system.

c) 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.

25. 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 distance from the Sun b) whether or not it has liquid water c) its size d) its composition

c) its size

1. The astrometric technique looks for planets with careful measurements of a star's _________. a) velocity towards or away from us b) brightness c) position in the sky d) all of the above

c) position in the sky

35. When you see the bright flash of a meteor, what are you actually seeing? a) emission of visible light from a particle that has not yet entered Earth's atmosphere b) a star that has suddenly shot across the sky c) the glow from a pea-size particle and the surrounding air as the particle burns up in our atmosphere d) the flash that occurs when a speeding rock from space hits the ground

c) the glow from a pea-size particle and the surrounding air as the particle burns up in our atmosphere

Which of the following best describes the internal layering of Jupiter, from the center outward?

core of rock, metal, and hydrogen compounds; thick layer of metallic hydrogen; layer of liquid hydrogen; layer of gaseous hydrogen; cloud layer

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?

countless icy particles, ranging in size from dust grains to large boulders

46. All of the following have occurred over long periods of time on Earth. Which one is not thought to have played a major role in long-term changes in Earth's climate? a) Changes in the Earth's axis tilt. b) Changes in the Earth's overall reflectivity. c) Changes in the atmospheric concentration of greenhouse gases. d) A gradual rise in the atmospheric content of oxygen.

d) A gradual rise in the atmospheric content of oxygen.

18. Why didn't a planet form where the asteroid belt is now located? a) The temperature in this portion of the solar nebula was just right to prevent rock from sticking together. b) There was too much rocky material to form a terrestrial planet, but not enough gaseous material to form a jovian planet. c) There was not enough material in this part of the solar nebula to form a planet. d) Gravitational tugs from Jupiter prevented material from collecting together to form a planet.

d) Gravitational tugs from Jupiter prevented material from collecting together to form a planet.

50. How do scientists determine the age of the solar system? a) Radiometric dating of Moon rocks. b) Theoretical calculations tell us how long it has taken the planets to evolve to their present forms c) Radiometric dating of the oldest Earth rocks. d) Radiometric dating of meteorites

d) Radiometric dating of meteorites

34. 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 Venus. Distance from Sun: same as Mars. Rotation rate: once every 25 hours. c) Size: same as Mars. Distance from Sun: same as Earth. Rotation rate: once every 18 hours. d) Size: same as the Moon. Distance from Sun: same as Mars. Rotation rate: once every 10 days.

d) Size: same as the Moon. Distance from Sun: same as Mars. Rotation rate: once every 10 days.

24. Which of the following correctly compares the Sun's energy generation process to the energy generation process in human-built nuclear power plants? a) The Sun generates energy through fission while nuclear power plants generate energy through fusion. b) Both processes involve nuclear fusion, but the Sun fuses hydrogen while nuclear power plants fuse uranium. c) The Sun generates energy through nuclear reactions while nuclear power plants generate energy through chemical reactions. d) The Sun generates energy by fusing small nuclei into larger ones, while our power plants generate energy by the fission (splitting) of large nuclei.

d) The Sun generates energy by fusing small nuclei into larger ones, while our power plants generate energy by the fission (splitting) of large nuclei.

38. How does the Sun's mass compare to Earth's mass? a) The Sun's mass is about 300 times the mass of the Earth. b) Both have approximately the same mass. c) The Sun's mass is about 30 times the mass of the Earth. d) The Sun's mass is about 300,000 times the mass of the Earth.

d) The Sun's mass is about 300,000 times the mass of the Earth.

2. 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 regions of the maria were hit by fewer impacts than the densely cratered regions. b) The maria formed within the past 1 billion years. c) Erosion affects the maria more than it affects other regions of the Moon. d) The maria formed after the heavy bombardment ended.

d) The maria formed after the heavy bombardment ended.

16. The Sun's surface seethes and churns with a bubbling pattern. Why? a) The Sun's surface is boiling. b) The churning gas is being stirred up by the strong solar wind. c) The churning is an illusion created by varying radiation, as the gas on the Sun's surface is actually quite still. d) We are seeing hot gas rising and cool gas falling due to the convection that occurs beneath the surface.

d) We are seeing hot gas rising and cool gas falling due to the convection that occurs beneath the surface.

12. Which of the following gases is not a significant ingredient of the jovian planet atmospheres? a) water b) hydrogen c) helium d) carbon dioxide

d) carbon dioxide

27. The discovery of Eris __________. a) was surprising, due to its "backwards" orbit around the Sun b) was not surprising, because the existence of a massive "Planet X" had been predicted nearly a century ago c) was surprising, since we thought we knew about all large objects in the solar system d) was not surprising, because other Kuiper belt objects approaching the size of Pluto had already been discovered

d) was not surprising, because other Kuiper belt objects approaching the size of Pluto had already been discovered

Orbital resonance also gives Europa an elliptical orbit, so it experiences tidal heating, too. However, Europa experiences less tidal heating than Io, because Europa __________ than Io.

is farther from Jupiter

Planetary rings are

known to exist for all of the jovian planets. nearer to their planet than any of the planet's large moons. orbiting in the equatorial plane of their planet. composed of a large number of individual particles that orbit their planet in accord with Kepler's third law.

What is differential rotation?

rotation where a body rotates faster or slower at its equator than it does at its poles