Deck 9: The Outer Planets

Question 1

Jupiter's mass makes up what fraction of the total mass of the planets in the solar system?

A) 70 percent
B) 10 percent
C) 98 percent
D) 50 percent

Answer 1

70 percent

Question 2

Which is the biggest planet in the solar system?

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

Answer 2

Jupiter

Question 3

When viewed from Earth, the apparent angular diameter of Jupiter appears to vary with time because

A) the amount of sunlight reaching Jupiter varies with time.
B) the absorption of radiation by interplanetary dust between Jupiter and Earth varies with time.
C) Jupiter is a fluid planet, and its size and brightness both pulsate with a long oscillation period.
D) the distance between Jupiter and Earth varies.

Answer 3

the distance between Jupiter and Earth varies.

Question 4

The mass of Jupiter compared with that of Earth is

A) about 300 times larger.
B) about 1/300 because of Jupiter's low density.
C) several thousand times larger.
D) about 11 times as large.

Question 5

How do the moons of Jupiter behave when considered in terms of the relationship between the period P and radius a of their orbits around the planet?

A) Jupiter's moons follow the Keplerian relationship P² = ka³, where k is a constant that is different from that in the relation governing planetary motion around the Sun.
B) Jupiter's moons do not obey the Keplerian relationship P² = ka³ because their motion about Jupiter is affected by Jupiter's motion about the Sun.
C) Jupiter's moons obey the Keplerian relationship P² = ka³ where k is the same as that for planetary motion around the Sun because it is a universal constant.
D) Jupiter's moons do not obey the Keplerian relationship P² = ka³ because they orbit Jupiter, not the Sun.

Question 6

How much more massive would Jupiter need to be to generate energy by nuclear fusion in its interior?

A) 1000 times more massive
B) It already generates energy by nuclear fusion.
C) only about twice as massive; it is almost a star
D) 75 times more massive

Question 7

The dark, reddish bands on Jupiter are called

A) streams.
B) zones.
C) voids.
D) belts.

Question 8

Which of these objects rotates the MOST quickly around its own axis?

A) Venus
B) Earth's Moon
C) Earth
D) Jupiter

Question 9

On which planet is the Great Red Spot found?

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

Question 10

What characteristic features are seen on the visible surface of Jupiter?

A) light and dark bands parallel to the equator
B) large volcanoes and a long, deep rift valley
C) bluish-green, almost featureless cloud layer
D) almost featureless white cloud surface

Question 11

The existence of the Great Red Spot of Jupiter has been known since

A) the arrival at Jupiter of Voyager 1, with its imaging cameras, in 1979.
B) the time of Hooke and Cassini in the 1600s.
C) first light at the 200-inch telescope on Mount Palomar, in 1948.
D) the first flyby of a spacecraft, Pioneer 10, in December 1973.

Question 12

To compute the density of Jupiter, one obtains its mass from

A) Kepler's third law and its size from Kepler's second law.
B) its observed rotation period and its size from trigonometry.
C) Kepler's third law and its size from trigonometry.
D) its gravitational redshift and its size from Kepler's first law.

Question 13

How does the amount of radiation radiated from Jupiter compare with the amount of radiation it receives from the Sun?

A) Jupiter receives more radiation than it radiates because of the external energy required to maintain its powerful magnetic field.
B) These two are in balance, as they must be.
C) Jupiter radiates about twice as much energy as it receives from the Sun.
D) Jupiter radiates almost 75 times as much energy as it receives from the Sun.

Question 14

What is the mass of Jupiter compared with other objects in the solar system?

A) 20 times the mass of all other planets combined
B) half the mass of the Sun
C) as large as the mass of Saturn and Neptune combined
D) about two and a half times the mass of all other planets combined

Question 15

Which spacecraft recently dropped a probe into the atmosphere of Jupiter?

A) Ulysses
B) Voyager
C) Cassini
D) Galileo

Question 16

How is the mass of Jupiter determined?

A) by observing Jupiter's interaction with the Sun and using Kepler's third law
B) by observing Jupiter's interaction with its satellites and using Kepler's third law
C) by multiplying Jupiter's density by its volume
D) by observing Jupiter's effect on the perihelion of Mercury

Question 17

What is the physical appearance of Jupiter as seen from Earth or a spacecraft?

A) uniform bluish color with a high-level haze
B) solid ice surface, showing some craters that have been highly modified by ice flow
C) densely cratered surface with one large impact basin
D) series of dark belts and light zones parallel to the equator

Question 18

Evidence of lava flow, either recent or ancient, is NOT found on

A) Jupiter.
B) Earth.
C) Earth's Moon.
D) Mars.

Question 19

Jupiter is sometimes described as a "failed star," suggesting that if it had more mass it would have developed as a star rather than as a planet and that we would live in a binary star system. Is this possible? How many times more massive would Jupiter have to be for this development to have taken place?

A) Yes. Jupiter would need only about double its present mass.
B) Yes. Jupiter would need slightly less than 100 times its present mass.
C) Yes, but Jupiter would need thousands of times its present mass.
D) No. No amount of extra mass could make a planet into a star.

Question 20

What are the light-colored bands on Jupiter called?

A) belts
B) streams
C) plumes
D) zones

Question 21

Jupiter's Great Red Spot is a(n)

A) continent.
B) storm.
C) optical illusion.
D) hole in the clouds.

Question 22

What is the Great Red Spot on Jupiter?

A) summit of a large mountain that rises above the upper cloud level
B) region over the south pole of Jupiter where ammonia compounds that absorb blue light have condensed in the colder atmosphere
C) area where charged particles from the satellite Io collide with Jupiter's cloud tops
D) large, long-lived hurricanelike storm that is maintained by the differential rotation of Jupiter's atmosphere

Question 23

Which planet in the solar system has the fastest rotation?

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

Question 24

One interesting feature of Jupiter's rotation is the fact that

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

Question 25

Detailed observations of Jupiter's rotation suggest that Jupiter

A) rotates in two separate parts, with equatorial regions rotating in a direction opposite to polar regions.
B) is slowing down noticeably at the present time.
C) rotates as a solid body, with equatorial and polar regions showing the same rotational period.
D) is not a rigid object because equatorial regions rotate faster than polar regions.

Question 26

Which of these likely plays an important role in the banded structure on Jupiter's visible "surface" as seen from Earth?

A) "sweeping" of Jupiter's clouds through magnetic field lines from Jupiter's magnetosphere
B) underlying rising and falling convection pattern stretched into bands by Jupiter's rapid rotation
C) underlying north-south flow pattern stretched into bands by Jupiter's rapid rotation
D) breaking up by underlying mountain ranges of the strong eastward flow caused by Jupiter's rapid rotation

Question 27

The lifetime of the Great Red Spot of Jupiter appears to be

A) well over 2000 years, from ancient Greek records.
B) about 2 to 4 weeks between successive appearances, similar to sunspots.
C) about one Jupiter orbital period between successive appearances because the spot is produced by tidal effects.
D) at least 300 years, from visual records.

Question 28

What is the dominant circulation pattern in Jupiter's atmosphere (i.e., at the visible "surface")?

A) alternating bands of eastward and westward flow parallel to the equator
B) air rising at the equator, flowing north and south toward the poles, then sinking and returning to the equator at a lower level
C) uniform eastward flow of the entire atmosphere, with occasional dark storms and turbulent swirls
D) isolated storms and turbulent swirls, with little overall flow pattern in any particular direction

Question 29

Which feature of Jupiter leads to the confinement of its clouds in very narrow bands around the planet?

A) high gravitational field
B) powerful magnetic field
C) the large proportion of hydrogen and helium in its atmosphere
D) rapid rotation

Question 30

The Great Red Spot is

A) the top of a massive mountain penetrating through Jupiter's clouds.
B) a temporary storm in Jupiter's atmosphere, lasting a few months.
C) a large, long-lived storm system in Jupiter's atmosphere.
D) the colored polar cap of Jupiter.

Question 31

The composition of the clouds seen on Jupiter is

A) similar to the composition of Earth's clouds throughout the whole atmosphere-water droplets and crystals of frozen water.
B) very different from the composition of Earth's clouds: almost entirely ammonia and ammonium hydrosulfide crystals and almost no water.
C) similar to the composition of Earth's clouds (water droplets and crystals of frozen water) in the higher levels but very different (ammonia crystals) in the lower levels.
D) similar to the composition of Earth's clouds (water droplets and crystals of frozen water) in the lower levels but very different (ammonia crystals and other chemicals) in the higher levels.

Question 32

What is the Great Red Spot?

A) dark, polar hood in the clouds of Titan, a satellite of Saturn
B) large storm on Neptune discovered by the Voyager spacecraft
C) lava lake on Io, a satellite of Jupiter
D) large and long-lived, possibly permanent storm on Jupiter

Question 33

What are the MOST common molecules in Jupiter's clouds?

A) ice crystals of water and carbon dioxide
B) liquid droplets of water and ammonia
C) ice crystals of methane, ammonia, and water vapor
D) water ice crystals

Question 34

Have astronomers observed differential rotation in the atmosphere of Jupiter?

A) No. The entire atmosphere rotates together.
B) Yes. The polar regions rotate slightly faster than the equatorial regions.
C) Yes. The equatorial regions rotate slightly faster than the polar regions.
D) Yes. The equatorial regions rotate much faster (approximately half the period) than the polar regions.

Question 35

Which of these conclusions is correct on the basis of observations of the motions of Jupiter's clouds?

A) The planet rotates differentially, with the equatorial regions rotating fastest while intermediate latitudes and polar regions rotate more slowly.
B) Intermediate-latitude regions rotate fastest while equatorial and polar regions rotate more slowly, as shown by the presence of bands and zones and locally rotating spots and ovals.
C) The planet rotates as a solid body because of its great mass and self-gravitation, with all regions having the same rotation speed.
D) The planet rotates differentially, with equatorial regions rotating slowest and rotation speed increasing toward both poles.

Question 36

The rotation period of Jupiter is

A) relatively short, on the order of 10 hours.
B) very short, on the order of 1 hour.
C) very long-several weeks-because of its great size and mass.
D) long, on the order of several days.

Question 37

One distinctive feature that is visible on the "surface" of Jupiter through a telescope from Earth is

A) the Great Red Spot.
B) Olympus Mons.
C) the Cassini Division.
D) the northern auroral oval.

Question 38

What is the overall composition, according to the number of atoms, of the outer atmospheric regions of Jupiter in terms of the relative numbers of atoms?

A) 75 percent hydrogen, 15 percent helium, and 10 percent everything else
B) hydrogen and helium only, with no other elements
C) 86 percent hydrogen, 13 percent helium, and 1 percent everything else
D) pure hydrogen

Question 39

Which of these chemicals is the MOST abundant in the outer atmosphere of Jupiter?

A) H₂O (water vapor)
B) CH₄ (methane)
C) NH₃ (ammonia)
D) CO₂ (carbon dioxide)

Question 40

The brown ovals seen in Jupiter's atmosphere appear bright in an image taken in infrared radiation. Why is this?

A) The ovals are moving toward Earth, and the Doppler blueshift makes them appear brighter.
B) The ovals are moving away from Earth, and the Doppler redshift makes them appear brighter.
C) The ovals are high up in the Jovian atmosphere.
D) The ovals are deep within the Jovian atmosphere.

Question 41

What is the basic structure of the planet Jupiter?

A) rocky core overlaid by a thick mantle of liquid hydrogen, relatively thin gaseous atmosphere
B) small rocky core overlaid by a thin mantle of liquid hydrogen, thick gaseous atmosphere
C) large rocky core with a thin mantle of liquid hydrogen, thin gaseous atmosphere
D) rocky core, liquid hydrogen mantle, and gaseous atmosphere, all having about the same thickness

Question 42

Which of these spacecraft did NOT visit Jupiter?

A) Galileo
B) Viking
C) Pioneer
D) Voyager

Question 43

How thick are the cloud layers on Jupiter's visible "surface"?

A) greater than 10,000 km, as seen through the dark ovals that represent holes in the cloud layers
B) about 1000 km
C) about 60 km
D) very thin, less than 10 km

Question 44

The internal structure of the two largest Jovian planets (from the center outward) is a(n)

A) iron-nickel core (from which the Jovian magnetic field arises), a semifluid rocky mantle, and a solid rocky crust covered by a thin atmosphere.
B) rocky core covered by a very thick gaseous hydrogen and helium layer.
C) rocky core, a liquid "ice" layer that may overlap with the rocky core, a liquid metallic hydrogen and helium layer, and an ordinary hydrogen and helium gaseous layer.
D) rocky core, a liquid methane mantle, and a gaseous methane atmosphere.

Question 45

Recent estimates suggest that the overall mass distribution between atomic components of Jupiter is

A) 50 percent hydrogen and 50 percent helium.
B) almost 100 percent hydrogen.
C) 75 percent hydrogen, 24 percent helium, and 1 percent heavier elements.
D) 86 percent hydrogen, 13 percent helium, and 1 percent heavier elements.

Question 46

Which of these correctly characterizes the composition of Jupiter's cloud layers?

A) hard surface just under the cloud layers, contrary to the understanding of Jupiter's atmospheric structure
B) no evidence at all of hydrogen in the atmosphere of Jupiter
C) vast quantities of invisible water vapor above the cloud layers
D) only traces of water vapor and many other chemical elements in the cloud layers that are very easily measured spectroscopically from Earth

Question 47

Jupiter's core consists of rocky material like that from which the terrestrial planets formed. How does Jupiter's core compare with Earth?

A) It constitutes the bulk of Jupiter's mass, even though its radius is only a few percent of Jupiter's.
B) It is considerably larger in mass than Earth but only a small fraction of Jupiter's total mass.
C) Because most of the terrestrial materials were in the inner part of the solar nebula, Jupiter's core is smaller than Earth in both size and mass.
D) Because of Jupiter's enormous rate of spin, the core is not spherical. So, the size is difficult to compare to Earth, but the core's mass appears to be smaller than Earth's mass.

Question 48

The high-speed winds observed on Jupiter occur mainly

A) in a northwest-southeast direction from the light zones toward the dark belts.
B) in a northeast-southwest direction from the dark belts toward the light zones.
C) from the poles toward the equator.
D) in the directions parallel to the equator.

Question 49

What have planetary scientists observed about the evolution of the red spots and white and brown ovals in Jupiter's atmosphere?

A) All of these seem to be permanent with no discernible changes over the 4 centuries of observing them.
B) Brown ovals routinely change into white ovals and then back into brown.
C) White ovals have been observed to merge to create a red spot.
D) The Great Red Spot seems too create and spin off other smaller red spots.

Question 50

Jupiter is significantly thicker through the equator than it is through the poles. The word used to describe such a planetary shape is

A) oblate.
B) obtuse.
C) oblique.
D) obese.

Question 51

Where in the solar system would one look for liquid hydrogen?

A) on the polar caps of Mars
B) on the surface of Venus, beneath the clouds
C) Nowhere, because it is not cold enough anywhere in the solar system to liquefy hydrogen
D) in the deep interiors of Jupiter and Saturn

Question 52

The predominant large-scale atmospheric circulation pattern on Jupiter is characterized by

A) strong winds blowing eastward at all latitudes so that the entire atmosphere rotates faster than the planet.
B) isolated cyclones (low-pressure areas) and anticyclones (high-pressure areas), similar to those on Earth.
C) strong winds blowing parallel to the equator but in opposite directions at different latitudes.
D) strong winds blowing westward at all latitudes so that the entire atmosphere rotates more slowly than the planet.

Question 53

What is the basic structure of the planet Jupiter?

A) rocky core, liquid hydrogen mantle, gaseous atmosphere
B) rocky core, liquid methane and water mantle, gaseous atmosphere
C) entirely liquid hydrogen except for a thin gaseous atmosphere
D) rocky core, frozen water mantle, thin methane atmosphere

Question 54

What did the Cassini spacecraft recently observe about the belts, zones, and ovals in Jupiter's atmosphere?

A) Cooler material (white ovals, dark belts) is generally rising.
B) Warmer material (brown ovals, white zones) is generally sinking.
C) White clouds have been seen rising in the dark belts.
D) Ovals occur in pairs, a white one and a brown one together.

Question 55

The overall interior structure of the Jovian planets is expected to be

A) three-layered: a rocky core covered by liquid metallic hydrogen and a thin gaseous hydrogen/helium atmosphere.
B) four-layered: a rocky core, a semifluid ice layer that may overlap with the rocky core, a liquid mantle of hydrogen, and a gaseous hydrogen and helium atmosphere.
C) two-layered: a large, solid, rocky core surrounded by an extensive gaseous atmosphere.
D) four-layered: a solid inner core, a liquid iron outer core, a semifluid rocky mantle, and a solid crust.

Question 56

In what form is the hydrogen in the interior of Jupiter?

A) liquid metallic hydrogen, electrically conducting
B) gaseous molecular hydrogen (H₂) electrically conducting
C) solid hydrogen, compressed to this state by the very high pressures
D) gaseous hydrogen because the pressures are never sufficient to condense it into liquid

Question 57

Which one of these does NOT contribute in a significant way to the energy radiated outward by Jupiter?

A) the decay of radioactive elements in the planet's core
B) reflection of radiation absorbed from the Sun
C) magnetic energy released by Jupiter's enormous magnetic field
D) gravitational potential energy released as Jupiter continues to contract

Question 58

What is the Kelvin-Helmholtz mechanism?

A) the tidal flexing that causes Io to be geologically active
B) A satellite in a nonequatorial orbit will have its orbit gradually shifted toward the equatorial plane.
C) the release of gravitational potential energy as heat when a body contracts
D) the shift of the spectral peak to longer wavelengths as a body cools off

Question 59

Which spacecraft was the MOST recent to reach Jupiter?

A) Hubble Space Telescope
B) Galileo
C) Pioneer
D) Voyager

Question 60

What material serves as the main electrical conductor in Jupiter's interior?

A) liquid metallic helium
B) solid metallic hydrogen
C) liquid metallic hydrogen
D) a molten iron-nickel mixture

Question 61

Which of these has NOT been observed on Jupiter?

A) long-lived storms
B) auroras
C) particle-trapping regions in the magnetic fields like Earth's Van Allen belts
D) currents in the atmosphere (like Earth's jet stream) which can stretch from the pole to the equator

Question 62

Jupiter has a magnetic field that is

A) much more powerful than that of Earth.
B) about the same strength and extent as that of Earth.
C) weak and variable, sometimes existing only above the Great Red Spot.
D) very weak, almost nonexistent.

Question 63

What is the source of Jupiter's intense magnetic field?

A) electric currents in ionized layers of Jupiter's atmosphere
B) electric currents in Jupiter's molten iron core
C) permanently magnetized iron core
D) electric currents in Jupiter's liquid hydrogen layer

Question 64

Which of the Galilean moons of Jupiter are within Jupiter's magnetosphere?

A) only Io; the others are well outside the magnetosphere.
B) only Io and Europa; the others are well outside the magnetosphere.
C) all except Callisto, which is well outside the magnetosphere
D) all four Galilean moons

Question 65

The magnetic field strength at Jupiter's "surface" exceeds that at Earth's equatorial surface by a factor of about

A) 20,000.
B) 1 million.
C) 14.
D) 2.

Question 66

At what locations are auroras seen on Jupiter?

A) directly above both magnetic poles, with little extension from these regions toward the equator
B) only over the major spots in the atmosphere, such as the Great Red Spot, where the magnetic field of Jupiter is disturbed
C) in oval regions around Jupiter's magnetic poles but only rarely, if ever, directly over these poles
D) along the equator, aligned with the dark bands and light zones

Question 67

The magnetosphere of Jupiter is

A) a region of charged particles extending along the orbit of the satellite Io, forming a ring around Jupiter.
B) the magnetized hydrogen in the inner regions of Jupiter just outside the solid core, where the planet's magnetic field is produced.
C) a narrow layer in Jupiter's atmosphere, just above the cloud tops, in which intense electric currents flow and generate the planet's magnetic field.
D) a large space around Jupiter in which its magnetic field has excluded the solar wind but that is filled with high-energy charged particles.

Question 68

Strong radio radiation from Jupiter indicates the presence of

A) radio stations.
B) thunderstorms.
C) a strong magnetic field.
D) the Great Red Spot.

Question 69

The shape and dimensions of the magnetosphere surrounding Jupiter are controlled by

A) the atoms of Jupiter's outer atmosphere moving outward because of the rapid rotation of the planet, pressing against the solar wind.
B) the pressure of the solar wind against the outer atmosphere of Jupiter.
C) solar radiation pressure pushing against the planet's outer atmosphere.
D) the opposing pressures of the ionized gas of the solar wind and the planet's magnetic field.

Question 70

The material in the interior of Jupiter that is thought to be responsible for its powerful magnetic field is

A) solid magnetic and magnetized iron.
B) liquid metallic hydrogen.
C) "ices" of NH₃ (ammonia), CH₄ (methane), and H₂O (water) that contain frozen-in magnetic fields.
D) molten iron and nickel.

Question 71

In which of these ways is there a similarity between Jupiter and Earth?

A) Jupiter and Earth display the same colors when viewed from space.
B) Auroras are produced by magnetospheres on both Jupiter and Earth.
C) The atmospheres of Jupiter and Earth contain the same constituency of gases.
D) Jupiter and Earth have similar average densities.

Question 72

If one could see Jupiter's magnetosphere visually, how big would it appear?

A) Jupiter's magnetosphere would be too small to be visible without a telescope.
B) Jupiter's magnetosphere would be easily visible, many times larger than the full Moon.
C) Jupiter's magnetosphere would cover essentially the entire sky whenever Jupiter was above the horizon.
D) Jupiter's magnetosphere would be just big enough to see, almost at the limit of unaided-eye visibility.

Question 73

How does the magnetosphere of Jupiter compare to that of Earth?

A) Jupiter's magnetosphere is very similar to that of Earth.
B) Jupiter's magnetosphere is much larger than that of Earth because of Jupiter's large magnetic field and the weakness of the solar wind at Jupiter's orbital distance from the Sun.
C) Jupiter has no detectable magnetic field and hence no magnetosphere.
D) Jupiter's magnetosphere is much smaller than that of Earth because Jupiter's magnetic field is much stronger than that of Earth.

Question 74

The requirement(s) for the generation of a powerful magnetic field in a Jovian planet (e.g., Jupiter, Saturn) appear(s) to be a

A) liquid "metal" core and interior, and very slow rotation.
B) solid iron core forming a permanent magnet.
C) liquid "metal" interior and relatively rapid rotation.
D) solid interior throughout the planet and slow rotation.

Question 75

If one could see the full extent of the magnetosphere of Jupiter from Earth, how big would it appear in the sky?

A) about 16 times larger than Jupiter itself
B) about as large as the full Moon
C) about twice as large as Jupiter itself
D) 16 times larger than the full Moon

Question 76

The low average density of Jupiter (about 1300 kg/m³ compared with that of water, 1000 kg/m³) indicates that this planet is composed mainly of

A) hydrogen and helium in gaseous form only because low temperatures and great pressures are needed to liquefy these gases.
B) water, compressed somewhat by gravity, maybe in the form of ice.
C) methane, ammonia, and water, from spectroscopic observation of its atmosphere.
D) hydrogen, in liquid or gaseous form.

Question 77

The magnetosphere of Jupiter is

A) a narrow layer in which intense electric currents flow, just above the cloud tops in the planet's atmosphere, generating the planet's magnetic field.
B) the inner regions of Jupiter, just beyond the solid core, that contain liquid metallic hydrogen, where electric currents flow to produce the planet's magnetic field.
C) a doughnut-shaped region similar to the Van Allen belts around Earth containing high-speed protons and electrons, whose motions produce the planet's magnetic field.
D) a large cavity created and maintained within the solar wind stream by the planet's magnetic field, filled with extremely hot, ionized plasma.

Question 78

What conditions are considered to be necessary for a planet to be able to generate an intense magnetic field?

A) ionized and electrically conducting layer in its atmosphere
B) electrically conducting material in its interior and slow rotation because rapid rotation will destroy a magnetic field
C) solid iron core into which a magnetic field was induced early in the planet's history
D) relatively rapid rotation and electrically conducting material in its interior

Question 79

The deepest central sections of the interiors of Jupiter and Saturn are thought to be composed of

A) methane, ammonia, and water vapor.
B) liquid metallic hydrogen.
C) magnetized iron.
D) rock.

Question 80

The Jovian planets have high masses and hence generate powerful gravitational fields, and yet they have low average densities. What does this fact indicate about their interiors?

A) The Jovian planets are composed almost entirely of ice crystals and dust.
B) The Jovian planets are composed almost entirely of water.
C) The interiors of the Jovian planets are hot and gaseous, like those of cool stars.
D) The Jovian planets are composed almost entirely of hydrogen and helium.