Deck 7: Comparative Planetology I: Our Solar System

Question 1

Our planetary system consists of:

A)one large planet, and many small planets of about the same size, all accompanied by small moons.
B)large and small planets, all of them accompanied by small moons, none of which is as large as a planet..
C)large and small planets, some accompanied by moons as large as the smaller planets.
D)a series of planets of about the same size, some of which are accompanied by moons, the largest of which are as big as the planets themselves.

Answer 1

C

Question 2

In our solar system, which of the following planets is not a member of the jovian group?

A)Mars
B)Saturn
C)Neptune
D)Jupiter

Answer 2

A

Question 3

Mars is a(n):

A)inner planet.
B)terrestrial planet.
C)jovian planet.
D)dwarf planet.

Answer 3

B

Question 4

Neptune is a(n):

A)inner planet.
B)terrestrial planet.
C)jovian planet.
D)dwarf planet.

Question 5

The planet with its orbit closest to a circle (least orbital eccentricity) in our planetary system is:

A)Uranus.
B)Neptune.
C)Earth.
D)Venus.

Question 6

The planet whose orbit is inclined at the lowest angle to the plane of the ecliptic is:

A)Mercury.
B)Earth.
C)Jupiter.
D)Neptune.

Question 7

How many orbits of the Sun (sidereal periods) has Neptune completed since its discovery? (See Table 7-1, Universe, 11th ed. (in the text).)

A)just more than 1
B)fewer than 1
C)about 147
D)more than 2

Question 8

What observations permit the mass of a planet to be most easily determined?

A)measurement of its albedo (reflectivity) and brightness in the sky
B)observation of its gravitational interaction with its moon
C)measurement of its excess infrared radiation as a measure of its gravitational shrinkage
D)measurement of its volume and density

Question 9

How can we determine the mass of a planet?

A)from the orbital parameters of one of its moons
B)by observing its gravitational influence on a passing comet
C)by observing its gravitational influence on the trajectory of a spacecraft
D)All of the above are correct.

Question 10

We can estimate a planet's density by knowing its size and:

A)its magnetic field.
B)its distance from the Sun.
C)how much it influences the motion of a nearby spacecraft.
D)its rotation rate.

Question 11

We can estimate the density of a planet's interior if we compare its overall density with the:

A)density of its surface materials.
B)density of its moons.
C)density of neighboring planets.
D)strength of its magnetic field.

Question 12

The best way to measure the mass of a planet is to measure the:

A)gravitational pull of the planet on an orbiting satellite or a nearby spacecraft.
B)speed of the planet in its orbit around the Sun.
C)size and rotational speed of the planet.
D)composition of the planet using spectroscopy.

Question 13

The average density of the outer "giant" planets compared to that of liquid water is:

A)much less than that of water.
B)about 1.2 times.
C)about 5 times.
D)greater than 10 times.

Question 14

The low average densities of the jovian planets, which have high masses and hence high gravitational fields, is an indication that their interiors are:

A)gaseous and have not condensed to liquid or solid form.
B)composed mainly of very light elements, such as H and He.
C)composed of very porous rock (many small, empty cavities).
D)composed of H₂O, CH₄ (methane), and NH₃ (ammonia).

Question 15

In order of increasing density, the terrestrial planets are:

A)Venus, Earth, Mars, and Mercury.
B)Earth, Mercury, Venus, and Mars.
C)Mars, Venus, Mercury, and Earth.
D)Mercury, Venus, Earth, and Mars.

Question 16

The largest of the terrestrial planets in our solar system is:

A)Jupiter.
B)Venus.
C)Mars.
D)Earth.

Question 17

The next planet beyond Saturn is Uranus. The distance from the orbit of Saturn to the orbit of Uranus is about the same as:

A)the distance from Saturn to the Sun.
B)the distance from Earth to the Sun.
C)the distance from the orbit of Earth to the orbit of Mars.
D)the distance from the orbit of Saturn to the orbit of Jupiter.

Question 18

Viewed from Earth, which planet has the smallest angular size?

A)Mercury
B)Mars
C)Jupiter
D)Neptune

Question 19

Volcanoes have been discovered on all of the following planets except one. Which one is the exception?

A)Earth
B)Venus
C)Mars
D)Uranus

Question 20

The natural satellites (moons) of the planets in our solar system:

A)fall into three main classes: three larger than Mercury, five others larger than our Moon, and the rest less than 300 km in diameter.
B)fall into two main classes: seven larger than 2000 km in diameter, the rest much smaller.
C)are all small, less than 2000 km in diameter.
D)are all approximately the size of our Moon or larger.

Question 21

Table 7-2 (in the text) describes the seven largest satellites in the solar system. From these data it can be seen that the presence of an atmosphere correlates with:

A)diameter. The largest satellites have atmospheres, the smaller ones do not.
B)mass. The more massive the satellite, the more likely the satellite is to have an atmosphere.
C)average density. The satellites with the larger average densities are more likely to have atmospheres.
D)None of the above is correct.

Question 22

Comparing Earth's Moon to the rest of the solar system, which contains about 130 known satellites, it is found that the Moon is:

A)a typical satellite of about average size.
B)the largest satellite in the solar system.
C)the largest satellite in the inner part of the solar system.
D)larger than some planets, including Mercury and Mars.

Question 23

How many moons in the solar system are larger than Earth's Moon? (See Table 7-2 of Universe, 11^th ed.)
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A)zero
B)one
C)two
D)four

Question 24

The wide absorption features in the optical spectrum of Titan's atmosphere (See Figure 7-3 of Universe, 11th ed.) are produced by:
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A)water vapor, H₂O.
B)methane gas, CH₄.
C)hydrogen gas, H₂.
D)oxygen gas, O₂.

Question 25

How do spectra of reflection of sunlight from a planet's surface compare with the spectra produced when this reflected light passes through the planet's atmosphere?

A)The surface produces only emission lines, the atmosphere produces only absorption lines.
B)The surface produces only absorption lines, the atmosphere produces only emission lines.
C)The surface spectra contain broad absorption lines, the atmosphere contains sharp absorption lines.
D)The surface spectra contain sharp absorption lines, the atmosphere contains broad absorption lines.

Question 26

The discovery of nitrogen gas (N₂) in the atmosphere of Titan was made by:

A)direct sampling of the atmosphere by a probe as it descended to Titan's surface.
B)ultraviolet spectroscopy from Earth.
C)measurement of microwave emission from N₂ molecules by radio telescopes on Earth.
D)infrared spectroscopy from the Cassini spacecraft.

Question 27

The composition of the solid surfaces of planets and satellites (moons) that do not have substantial atmospheres can be found by:

A)measuring the thermal emission from the surface at several wavelengths in the microwave and infrared regions of the spectrum.
B)comparing the spectrum of the sunlight reflected from the surface with the spectrum of direct sunlight from the Sun.
C)comparing very broad absorption features in their spectra with spectra of known substances on Earth.
D)measuring the wavelengths of narrow absorption lines in their spectra.

Question 28

How does spectroscopy help determine the composition of a planet's atmosphere?

A)Radiation emitted by the planet passes through the atmosphere on its way to Earth, and analysis of the resulting absorption spectrum gives clues to the atmosphere's composition.
B)Heat from the planet makes its atmosphere emit large amounts of radiation. Analysis of the resulting emission spectrum gives clues to the atmosphere's composition.
C)Light from the Sun passes through the planet's atmosphere before and after reflecting from the planet's surface. Analysis of the resulting absorption spectrum gives clues to the atmosphere's composition.
D)At present, the only way to determine the composition of a planet's atmosphere is to have a flyby spacecraft scoop up a sample and then analyze it with an on-board spectrometer.

Question 29

A laboratory on the surface of Earth makes a spectrum of radiation that originates at the Sun and reflects off a celestial body with an atmosphere such as Saturn's large satellite Titan. Which one of the following statements about the resulting spectrum is correct?

A)The reflection from the solid surface produces sharp spectral lines.
B)Earth's atmosphere contributes only very broad spectral features, not sharp lines, to the spectrum.
C)The atmosphere of the body can contribute sharp absorption lines to the spectrum.
D)There is no evidence in the spectrum of the solar origin of the radiation.

Question 30

To an astronomer, the word "ice" can mean:

A)water (H₂O), carbon dioxide (CO₂), methane (CH₄), or ammonia (NH₃).
B)hydrogen (H₂), water (H₂O), carbon dioxide (CO₂), methane (CH₄), or ammonia (NH₃).
C)only water (H₂O).
D)water (H₂O) or carbon dioxide (CO₂).

Question 31

If the atmosphere of a particular planet is at a temperature of 213 K (-60°C), then molecules of methane (CH₄) and molecules of carbon dioxide (CO₂) in this atmosphere have:

A)different average speed and kinetic energy.
B)the same average kinetic energy (but different average speed).
C)the same average speed (but different average kinetic energy).
D)the same average speed and kinetic energy.

Question 32

A nitrogen molecule (N₂) has a mass of 4.7 × 10^-26 kg, and a carbon dioxide molecule (CO₂) has a mass of 7.3 × 10^-26 kg. On a day when the temperature is 18°C (64°F), the N₂ molecules will have a:

A)greater average kinetic energy and greater average speed than the CO₂ molecules.
B)smaller average kinetic energy but greater average speed than the CO₂ molecules.
C)smaller average speed than the CO₂ molecules but the same average kinetic energy.
D)greater average speed than the CO₂ molecules but the same average kinetic energy.

Question 33

Each type of molecule has the same average kinetic energy in a planetary atmosphere. As a result (and knowing that an oxygen [O₂] molecule has twice the mass of a methane [CH₄] molecule), we can say that in this atmosphere the average speed of an oxygen molecule is:

A)1.4 times less than that of a methane molecule.
B)half that of a methane molecule.
C)twice that of a methane molecule.
D)1.4 times greater than that of a methane molecule.

Question 34

An oxygen (O₂) molecule has twice the mass of a methane (CH₄) molecule. In a planet's atmosphere at some particular temperature, the average kinetic energy of an oxygen molecule is:

A)the same as that of a methane molecule (that is, all molecules have the same average kinetic energy at the same temperature).
B)1.4 times greater than that of a methane molecule (that is, the average kinetic energy increases in proportion to the square root of the mass).
C)4 times greater than that of a methane molecule (that is, the average kinetic energy increases in proportion to the square of the mass).
D)twice that of a methane molecule (that is, the average kinetic energy increases in the same proportion as the mass).

Question 35

The average speed of methane molecules (CH₄, molecular mass = 2.66 × 10^-26 kg) in the atmosphere of Neptune (temperature = 63 K = -210°C) is:

A)313 m/s.
B)327,000 m/s.
C)572 m/s.
D)98,000 m/s.

Question 36

Most of the ammonia on Jupiter is in the form of a:

A)gas.
B)liquid.
C)solid.
D)plasma.

Question 37

On Mars, the temperature can reach 290 K and the escape speed is 5.0 km/sec. What is the average speed of a carbon dioxide molecule (mass = 7.31 × 10^-26 kg) at this temperature, and what can you say about the retention of carbon dioxide on Mars?

A)The average speed is 0.4 km/sec, so Mars should retain its carbon dioxide.
B)The average speed is 0.4 km/sec, so Mars should lose its carbon dioxide.
C)The average speed is 1.9 km/sec, so Mars should retain its carbon dioxide.
D)The average speed is 1.9 km/sec, so Mars should lose its carbon dioxide.

Question 38

The average speed of hydrogen molecules (H₂) in Earth's atmosphere is below the calculated escape speed from Earth (11.2 km/s). So, is hydrogen gas retained in Earth's atmosphere?

A)Yes. Under these conditions H₂ must be retained.
B)No. Escape speed depends on the mass of the escaping object. Hydrogen is the lightest molecule, thus its escape speed is well below 11.2 km/s.
C)No. Escape speed depends on the mass of the escaping object. Hydrogen is the lightest molecule, thus its escape speed is well above 11.2 km/s.
D)No. While the average speed of H₂ is below the escape speed, there will be some H₂ molecules with speeds above escape speed-and these will escape.

Question 39

The asteroid Vesta, located in the main asteroid belt between the orbits of Mars and Jupiter, is spherical in shape with a radius of 265 km and a mass of 3.0 × 10²⁰ kg. What is the minimum speed at which you could propel yourself upward and not fall back down?

A)285,000 m/s
B)0.28 m/s
C)388 m/s
D)534 m/s

Question 40

What relationship must exist between a certain molecule's average speed, v, in a planetary atmosphere and the escape velocity, V_esc, from the planet's surface for this particular molecular species to be retained by the planet?

A)v should not exceed V_esc.
B)v must be less than about 6 × V_esc.
C)v must be less than about 1/6 V_esc.
D)v should not exceed 2 × V_esc.

Question 41

The mass of the planet Jupiter is high and its atmosphere is relatively cool. What are the chances for the retention of gases within its atmosphere?

A)good for light (H₂ and He) molecules but poor for heavier (CH₄, NH₃, H₂O) molecules
B)good for all gases, including light (H₂ and He) and heavier (CH₄, NH₃, H₂O) molecules
C)poor for all gases because of the low temperature, thus all gases will be leaving Jupiter continuously
D)good for heavier (CH₄, NH₃, H₂O) molecules but poor for light (H₂ and He) molecules

Question 42

A molecule moves within the atmosphere of a planet. It would be less likely that this molecule would be retained in the atmosphere of this planet if the:

A)molecule were more massive.
B)planet were more massive.
C)planet's atmosphere were hotter.
D)planet's magnetic field were stronger.

Question 43

A typical asteroid is

A)spherical and densely covered with craters.
B)potato shaped with large and small craters.
C)potato shaped with a smooth, metallic surface.
D)spherical but distorted by seismic and volcanic activity.

Question 44

How big is Ceres, the largest asteroid?

A)It is larger than Mercury.
B)Its diameter is about the length of California.
C)It is about the size of Rhode Island.
D)It is the size of two football fields.

Question 45

Pluto is now classified as a(n):

A)planet.
B)minor planet.
C)asteroid.
D)trans-Neptunian object.

Question 46

Which of the large trans-Neptunian objects has the longest orbital period about the Sun?

A)Quaoar
B)Sedna
C)Pluto
D)Eris

Question 47

Suppose we discover a comet that is an elliptical orbital plane perpendicular to the ecliptic. What is the most likely place of origin of this comet?

A)the Oort cloud
B)the Kuiper belt
C)the asteroid belt
D)outside the solar system

Question 48

Which one of the following planets shows the greatest amount of cratering on its surface?

A)Mercury
B)Earth
C)Mars
D)Jupiter

Question 49

Which of the following planets shows the least amount of cratering on its surface?

A)Mercury
B)Earth
C)Mars
D)Jupiter

Question 50

Planets and satellites with a large amount of surface cratering generally have insignificant atmospheres. Why are these two conditions correlated?

A)The impacts that create the craters also tend to vaporize the atmosphere.
B)A large amount of cratering implies a small size, and this, in turn, implies a low escape speed.
C)A large amount of cratering implies a small size, and this, in turn, implies a high escape speed.
D)Most of the solar system debris that caused cratering was near the Sun. Thus, heavily cratered planets and satellites are near the Sun where high temperatures result in high average molecular speeds.

Question 51

The craters on the Moon are all nearly circular. Why is this?

A)Most of the craters on the Moon were formed by volcanoes, and this results in circular craters.
B)It is believed that the objects that formed the impact craters on the Moon's surface all struck the Moon approximately perpendicular to its surface, and this would result in circular craters.
C)The objects that produced the impact craters came in at a variety of angles, but the craters were actually made by the shock waves generated by impact-and this results in circular craters.
D)The objects that produced the impact craters had been rounded by many previous collisions in space, and round objects produce circular craters regardless of their direction of impact.

Question 52

Evidence of cratering by the impact of massive objects is found:

A)throughout the solar system.
B)only in the inner part of the solar system.
C)only in the outer part of the solar system.
D)only on the satellites of the planets and not on the planets themselves.

Question 53

In general, large bodies in the solar system show less evidence of cratering than do small bodies. Why should we expect this correlation?

A)The gravity of large bodies deflects incoming projectiles and thus there are fewer collisions.
B)Large bodies are more likely to retain an atmosphere, and thus most large projectiles burn up before striking the ground.
C)Large bodies actually receive more hits because of their larger size, but later craters obliterate earlier ones, and we only see evidence of the most recent.
D)Large bodies cool more slowly and are more likely to retain internal heat and be geologically active, capable of resurfacing the planet and obliterating craters.

Question 54

Compare two moons, one with a diameter twice the size of the other. In general, the larger moon would be expected to have the:

A)older surface and more cratering per unit area.
B)older surface and less cratering per unit area.
C)younger surface and more cratering per unit area.
D)younger surface and less cratering per unit area.

Question 55

In general, we expect moons-some of the smaller bodies in the solar system-to show little geologic activity. An important exception to this rule is:

A)the Moon.
B)Io.
C)Rhea.
D)Dione.

Question 56

In order to produce a planet-wide magnetic field, a planet must have in its interior some material capable of carrying the electric current in such a way as to produce a dynamo effect. All of the following substances appear to be able to fill this role, except one. Which is the exception?

A)molten iron
B)solid iron
C)liquid metallic hydrogen
D)a liquid water-ammonia mixture under high pressure

Question 57

In general, a heavily cratered surface should imply a solid interior. Lack of a planet-wide magnetic field should also imply a solid interior. Which one of the following bodies actually possesses both a heavily cratered surface and no planet-wide magnetic field?

A)Mercury
B)Venus
C)the Moon
D)Mars

Question 58

In general, planets with interiors that are assumed to be molten are also expected to possess planet-wide magnetic fields. Which planet below is believed to have a molten interior and no planet-wide magnetic field?

A)Earth
B)Venus
C)Mercury
D)Mars

Question 59

All of the following conditions except one appear to be necessary in order for a planet or satellite to produce a planet-wide magnetic field by the dynamo effect. Which is the exception?

A)an interior that is at least partially liquid
B)an interior containing material that can conduct an electric current
C)relatively rapid rotation around its axis
D)a rotation axis that tilts only slightly with respect to the ecliptic

Question 60

In general, small bodies in the solar system are less likely than large bodies to possess a planet-wide magnetic field. Why should we expect size and magnetism to be correlated?

A)A small body cools more rapidly and is less likely to possess a molten, liquid interior-one requirement for planet-wide magnetism.
B)Small bodies are more likely to be heavily cratered, and such impacts can destroy the mechanism that produces the magnetic field.
C)Magnetic fields are produced by the entire volume of a body. Smaller bodies have smaller volumes and hence smaller magnetic fields.
D)Small bodies necessarily rotate more slowly, and a rapid rotation rate is one requirement for a planet-wide magnetic field.

Question 61

Mercury is small enough to have lost most of its internal heat, but it still has enough to produce a magnetic field. What is thought to be the source of this heat?

A)proximity to the Sun
B)tidal forces
C)residual heat from formation
D)volcanic activity

Question 62

A general summary of the planets in our solar system is that:

A)despite differences in size, the planets are remarkably similar.
B)the magnetic fields are all produced in the same way, but differences in planet size result in different field strengths.
C)the planets are remarkably different in size, magnetic field strength, and magnetic field generation method.
D)the terrestrial planets vary dramatically, but the jovian planets are remarkably similar.

Question 63

Which one of the following is more or less uniform across the planets of our solar system?

A)density
B)magnetic field strength
C)direction of orbital motion around the Sun
D)extent of cratering