Deck 12: Jupiter and Saturn: Lords of the Planets

Question 1

The mass of Jupiter is 317.8 times that of Earth. What would be the force of gravity exerted by Jupiter on a spacecraft at a distance of 1 au from Jupiter compared to that exerted on the same spacecraft by Earth at 1 au from Earth?

A)(317.8)² or about 101,000 times as large
B)1/317.8 as large
C)317.8 times as large
D)the same magnitude of force

Answer 1

C

Question 2

The fraction of the mass of the planetary system (excluding the Sun) that is concentrated in the planet Jupiter is about:

A)70%.
B)10%.
C)98%.
D)50%.

Answer 2

A

Question 3

Assuming all objects listed are visible, on a clear, moonless night the brightest object in the sky is:

A)Venus.
B)Sirius.
C)Jupiter.
D)Saturn.

Answer 3

A

Question 4

Suppose one of the outer planets begins retrograde motion every 12.5 months. From this we can determine that the orbital period of the planet is approximately:

A)12.5 months.
B)12.5 years.
C)24 years.
D)48 years.

Question 5

The lifetime of the Great Red Spot appears to be:

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

Question 6

The Great Red Spot is:

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

Question 7

The dark, reddish bands across the surface of Jupiter are known as:

A)great circles.
B)brown ovals.
C)zones.
D)belts.

Question 8

Suppose a planet is discovered in a prograde circular orbit with an orbital radius of 100 au. The time from opposition to opposition, viewed from Earth, will be longer than 1 Earth year. How much longer?

A)only a few seconds
B)about 9 hours
C)3.65 years
D)about 5 weeks

Question 9

Jupiter's mass is more than 300 times the mass of Earth, and Saturn has almost 100 times Earth's mass. These masses were determined by:

A)watching carefully the orbits of these planets around the Sun.
B)measuring the deviations of the other planets from their expected orbits around the Sun.
C)measuring the deflection of Halley's comet from its orbit when it is near Jupiter and Saturn.
D)measuring the orbits of the satellites of these planets.

Question 10

Which of the following exhibits differential rotation?

A)Earth
B)Jupiter
C)Ganymede
D)Callisto

Question 11

Which of the following exhibits differential rotation?

A)the Moon
B)Mars
C)Titan
D)Saturn

Question 12

What are the fractional proportions of the components that make up the mass of Jupiter?

A)almost pure hydrogen, with at most about 1% rock in the core
B)50% hydrogen, 49% helium, 1% rocky core
C)71% hydrogen and helium, 25% rocky core, 4% everything else
D)95% hydrogen and helium, 5% everything else

Question 13

Hydrogen and helium are the major constituents of Jupiter, but they proved hard to detect. Which one of the following was NOT a reason for this difficulty?

A)The spectral signatures of these molecules contain few prominent visible lines.
B)Ultraviolet radiation is absorbed in Earth's atmosphere.
C)Jupiter is always very far away from Earth and from the Sun.
D)The hydrogen and helium on Jupiter exist only in solid form deep under the atmosphere, and they emit very little radiation.

Question 14

The ammonia and methane in the atmosphere of Jupiter proved hard to detect because:

A)these molecules exist only in trace amounts in the atmosphere of Jupiter.
B)these molecules radiate mostly ultraviolet light, and this does not penetrate Earth's atmosphere.
C)these molecules radiate mostly long wavelengths, and these tend to scatter during the journey from Earth to Jupiter.
D)these molecules are unknown on Earth, so there spectra were not immediately recognized.

Question 15

Each of the following provides evidence for the large amount of hydrogen in the atmosphere of Jupiter EXCEPT one. Which is the exception?

A)differential rotation
B)calculation of the overall density of Jupiter
C)detection of methane (CH₄) in the atmosphere
D)detection of ammonia (NH₃) in the atmosphere

Question 16

If Jupiter and Saturn formed with the same chemical composition, why does Jupiter have more detectable helium than does Saturn?

A)Jupiter, being larger, has attracted more helium-bearing comets to add to its original composition.
B)Saturn has the smaller escape speed and much of its original helium has escaped.
C)Saturn's atmosphere is colder, and some of its helium has condensed and dropped to lower altitudes where it is harder to detect.
D)At Saturn's colder temperature, helium forms compounds, which decreases the amount of atomic helium.

Question 17

How permanent are the features we observe in Jupiter's atmosphere?

A)They appear quite permanent. Even the Great Red Spot has not changed in the four centuries it has been observed.
B)The white ovals come and go and sometimes merge, but the belt and zone structure remains unchanged.
C)The belt and zone structure has been observed to change, but the spots and ovals appear permanent.
D)The belts and ovals have both been observed to change.

Question 18

How do we know the nature of the white ovals in Jupiter's atmosphere?

A)They glow brightly in infrared, thus we know they are warm, high-altitude clouds.
B)They glow brightly in infrared, thus we know they are holes in the atmosphere that allow the escape of infrared from warmer, deeper layers.
C)The white matches other features at that level, so we know they form a continuous part of that atmospheric layer.
D)They glow dimly in infrared, thus we know they are actually at higher, colder levels in the atmosphere.

Question 19

How do we know the nature of the brown ovals in Jupiter's atmosphere?

A)They glow brightly in infrared, thus we know they are warm, high-altitude clouds.
B)They glow brightly in infrared, thus we know they are holes in the atmosphere that allow the escape of infrared from warmer, deeper layers.
C)The brown color matches other features at that level, so we know they form a continuous part of that atmospheric layer.
D)They glow dimly in infrared, thus we know they are actually at higher, colder levels in the atmosphere.

Question 20

Compared to the brown ovals in Jupiter's atmosphere, the white ovals are:

A)more transient, colder, and lower in altitude.
B)more transient, warmer, and lower in altitude.
C)longer lasting, colder, and higher in altitude.
D)longer lasting, warmer, and higher in altitude.

Question 21

The Cassini observations of Jupiter suggest that, contrary to previous models, the light-colored zones on Jupiter are:

A)volcanic plumes that have been stretched around the planet by Jupiter's high speed of rotation.
B)holes in the atmosphere through which lighter, deeper layers can be seen.
C)regions in which the gas is falling.
D)regions in which the gas is rising.

Question 22

The Cassini observations of Jupiter suggest that, contrary to previous modes, the dark belts on Jupiter are:

A)holes in the cloud bank through which the dark planet surface can be seen.
B)regions in which the gas is falling.
C)dust clouds from volcanoes that have been spread around the planet by very strong winds.
D)regions in which the gas is rising.

Question 23

When viewed in the infrared light emitted by the clouds, the brightest parts of Jupiter are:

A)in the belts, which correspond to deeper and hotter regions.
B)directly along the equator, where sunlight is most direct and effective in heating the gas.
C)in the zones, corresponding as expected to brighter regions in visible light.
D)over the north and south magnetic poles, where magnetospheric interaction heats the atmosphere.

Question 24

The dark-colored belts on Jupiter are brighter than the surrounding regions when viewed in infrared or heat radiation because:

A)chemical reactions causing the dark, visible colors also release energy and heat these regions.
B)these regions are composed of hot dust and gases released from volcanoes and distributed around the planet by high winds.
C)these regions are higher in Jupiter atmosphere, receive more sunlight, and hence are hotter in IR radiation.
D)these regions are deeper and therefore hotter layers of gas in Jupiter's atmosphere.

Question 25

The white spots observed in Saturn's atmosphere are believed to be crystals of:

A)ammonia.
B)water vapor.
C)methane.
D)hydrogen.

Question 26

Which of the following chemicals is the least abundant in the atmosphere of Jupiter?

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

Question 27

The composition of Jupiter's clouds is:

A)liquid droplets of water and ammonia.
B)ice crystals of water, ammonium hydrosulfide, and carbon dioxide.
C)water-ice crystals.
D)ice crystals of ammonia, ammonium hydrosulfide, and water.

Question 28

An astronomer detects a new feature in Jupiter's atmosphere. Subsequent observation shows that this feature is brighter than its surroundings when observed in infrared light. We can conclude that this feature is a:

A)localized storm feature.
B)region of higher density in the ammonium hydrosulfide layer.
C)region of high-altitude clouds created by upwardly moving winds.
D)deeper layer observed through a hole in Jupiter's clouds.

Question 29

Saturn's rotation rate is very fast but slower than Jupiter's. The wind speed at Saturn's equator, compared to the wind speed at Jupiter's equator, is:

A)smaller than Jupiter's because Saturn's rotation rate is less.
B)smaller than Jupiter's because Saturn's mass is less.
C)smaller than Jupiter's because of Saturn's smaller radius.
D)larger than Jupiter's for reasons not completely understood.

Question 30

The high-speed winds observed on Jupiter occur mainly:

A)in a north-south direction from the dark belts toward the light zones.
B)near the centers of the dark belts.
C)at the boundaries between the dark belts and the light zones.
D)near the centers of the light zones.

Question 31

On Jupiter and Saturn the wind currents move generally:

A)parallel to the equator.
B)from north to south.
C)from south to north.
D)in totally random directions.

Question 32

What are zonal winds on Jupiter?

A)winds blowing horizontally northward and southward above the cloud layer
B)winds blowing vertically upward and downward in regions of strong convection
C)winds blowing horizontally in a circular pattern, such as around the Great Red Spot
D)winds blowing horizontally eastward and westward in the cloud layer

Question 33

The source of excess heat emitted by Jupiter, above that which is absorbed as sunlight and reemitted, is thought to be:

A)heat generated in the interior by the same electrical currents that generate the planet's magnetic field.
B)heat caused by friction between oppositely directed winds at mid-latitudes.
C)gravitational potential energy released as heat during its formation stages, still being released.
D)chemical reactions between methane, ammonia, and water in the planet's atmosphere and clouds.

Question 34

We have discovered that the temperature in Jupiter's atmosphere increases as one moves inward toward the planet, and that the planet gives out more energy than it receives from the Sun. What is the cause of this?

A)the greenhouse effect
B)the Kelvin-Helmholtz contraction
C)nuclear reactions in Jupiter's interior
D)radioactivity in minerals in Jupiter's rocky core

Question 35

Because its interior is so hot, Jupiter radiates about twice as much heat as it receives from the Sun. How does this fraction compare with the excess energy radiated by Earth as a fraction of the energy Earth receives from the Sun?

A)It is about the same.
B)The fraction is about 10 times larger for Jupiter.
C)The fraction is about 1000 times larger for Jupiter.
D)The fraction is about 10⁴ times larger for Jupiter.

Question 36

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

A)very thin-only about 10 km
B)greater than 10,000 km, as seen through the dark ovals, holes in the cloud layers
C)about 100 km
D)about 1000 km

Question 37

One unsolved question about Jupiter and Saturn is:

A)why Jupiter radiates more energy than it receives from the Sun.
B)why Saturn is more effective than Jupiter in terms of radiating excess energy.
C)why wind speeds on Saturn are greater than those on Jupiter.
D)why Saturn's cloud layers are more spread out than Jupiter's.

Question 38

Jupiter and Saturn each have the same three basic cloud layers, but the spacing of the layers differs on the two planets. Why is this?

A)Jupiter's greater gravity has compressed the layers, so they are closer together there.
B)Jupiter's greater rotation rate has flung the layers outward, so they are separated more there.
C)Jupiter's warmer temperature has expanded the atmosphere, so they are more separated there.
D)On Saturn, the "rain" of helium condensate has forced the lower layers downward, so they are more separated there.

Question 39

Spectroscopy of Jupiter and Saturn has revealed atmospheres containing large quantities of which of the following gases, in addition to hydrogen and helium?

A)nitrogen (N₂), oxygen (O₂), and water vapor (H₂O)
B)methane (CH₄), ammonia (NH₃), and water vapor (H₂O)
C)clouds of sulfuric acid droplets (H₂SO₄)
D)carbon dioxide (CO₂) and traces of water vapor (H₂O)

Question 40

One observational fact that is common to both Jupiter and Saturn is that:

A)both planets appear cooler than is expected on the basis of received solar energy and emit less radiant energy than expected.
B)the temperature appears to fall continuously as depth into these planets increases, leading to the conclusion that the interiors of these planets are probably extremely cold.
C)CO₂ in their atmospheres appears to produce an intense greenhouse effect with very enhanced atmospheric temperatures of greater than 200°C in the outer layers.
D)both planets emit more energy (in the form of infrared radiation) than they receive from the Sun.

Question 41

Saturn appears to emit heat as infrared radiation in excess of the energy absorbed from sunlight and also the Kelvin-Helmholtz contraction. The most likely major cause of this excess heating is:

A)the condensing of helium into droplets that fall into the planet, releasing gravitational energy as heat.
B)the radioactive decay of naturally occurring isotopes in the atmosphere and interior of Saturn.
C)energy released from the continuous shrinking and condensation of this fluid planet.
D)remnant heat from the original formation of the planet.

Question 42

The relative proportions of hydrogen and helium that the Galileo Probe found in the atmosphere of Jupiter were almost exactly the same as in the Sun (as was expected), but the abundances of carbon, nitrogen, and sulfur were proportionally higher than in the Sun. What is believed to be the reason for this?

A)The probe probed an anomalous region where abundances were abnormal compared to the rest of Jupiter.
B)Jupiter formed farther out from the Sun than it is now, where temperatures are colder.
C)Comets and asteroids plunging into Jupiter brought heavier elements with them.
D)The lighter elements collect preferentially in the core, leaving an excess of heavier elements in the atmosphere.

Question 43

The relative proportions of hydrogen and helium that the Galileo Probe found in the atmosphere of Jupiter were almost exactly the same as in the Sun (as was expected), but the noble gases argon, krypton, and xenon were three times as abundant in Jupiter's atmosphere than in the Sun's. Which of the following ideas is considered to be a possible reason for this?

A)Jupiter formed farther out from the Sun than it is now, where temperatures are colder.
B)Jupiter formed closer to the Sun than it is now, where temperatures were warmer.
C)The noble gases do not combine with any other elements and floated to the "surface" (atmosphere) of Jupiter.
D)The probe probed an anomalous region where abundances were abnormal compared to the rest of Jupiter.

Question 44

The Galileo Probe found that the wind speed was an almost constant 650 km/h over the entire 200 km of its descent below Jupiter's cloud tops. What does this result imply for Jupiter?

A)Jupiter must have a solid surface within about 500 km below the clouds.
B)Jupiter cannot have a solid surface.
C)Solar heating of Jupiter's atmosphere is much more efficient than was previously thought.
D)Jupiter's atmospheric circulation is driven primarily by the escape of internal heat.

Question 45

The Galileo Probe made all of the following measurements, most of which gave unexpected results. Which result was expected?

A)The amounts of carbon, nitrogen, and sulfur are greater than solar abundances.
B)The amounts of argon, krypton, and xenon are greater than solar abundances.
C)No water clouds were encountered in the atmosphere.
D)Only traces of ammonia and ammonium hydrosulfide clouds were found.

Question 46

Which statement reflects the measured abundances of noble gases on Jupiter?

A)The abundances of noble gases on Jupiter are the same as those on the Sun, as they must be since noble gases do not take part in chemical reactions.
B)The noble gas abundances on Jupiter are lower than those on the Sun. We assume an early collision with a major planetesimal stripped Jupiter of much of its noble gas content.
C)The noble gas abundances on Jupiter are higher than those on the Sun. This can be accounted for by solid planetesimals striking Jupiter at its present location.
D)The noble gas abundances on Jupiter are higher than those on the Sun. This cannot be accounted for by solid planetesimals striking Jupiter at its present location, because it is not cold enough there to allow noble gases in frozen form. The planetesimals must have been added to Jupiter when it was farther out in the early solar system.

Question 47

Why were the high concentrations of noble gases found in Jupiter's upper atmosphere such a surprise?

A)Noble gases are not generally found in the outer solar system.
B)At Jupiter's distance from the Sun, it was too warm for these gases to solidify when the planets were forming.
C)These elements normally combine with other elements and are not found directly.
D)High concentrations are only found in the atmospheres of terrestrial planets.

Question 48

Oblateness is a measure of the:

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

Question 49

The oblateness of a planet does NOT depend upon:

A)its rotation rate.
B)whether its rotation about its axis is prograde or retrograde.
C)the fraction of its composition that is solid.
D)the fraction of its composition that is fluid (liquid or gas).

Question 50

A hypothetical planet has a diameter, measured through the equator, of 100,000 km and a diameter, measured through the poles, of 90,000 km. Its oblateness is therefore:

A)9%.
B)10%.
C)11%.
D)90%.

Question 51

The reason for the slightly flattened or oblate shape of Jupiter is:

A)its rapid rotation rate.
B)its cloud cover, more clouds forming over the equator on average.
C)that it was formed that way in the beginning and has maintained this shape.
D)the gravitational pull of the Sun and the other planets in the ecliptic.

Question 52

Jupiter appears as a flattened, oblate spheroid in the sky because:

A)it is spinning rapidly, and is composed mostly of fluid matter.
B)it was formed in this way at the time of planetary formation, and has solidified to this shape.
C)tidal distortion from its moons and from the Sun have distorted its shape.
D)it is moving rapidly around its orbit, flattening its shape.

Question 53

The three-dimensional shape of Jupiter is:

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

Question 54

The oblateness of Jupiter, which is a measure of the amount by which its polar diameter is less than its equatorial diameter and is a consequence of its fluid structure and rapid rotation, is:

A)0, or perfectly spherical, because the planet is fluid.
B)6.5%.
C)10%.
D)32%.

Question 55

The oblateness of Saturn, due to its composition and rapid rotation, is:

A)0.34%.
B)6.5%.
C)9.8%.
D)0.

Question 56

Saturn's oblateness is about half again as large as Jupiter's. Which one of the following changes would result in Jupiter having the same oblateness as Saturn?

A)Jupiter becomes more massive without changing its relative composition.
B)Jupiter's rocky core becomes more massive and its liquid metallic hydrogen mantle less massive.
C)Jupiter rotates more rapidly.
D)Jupiter's liquid ices solidify.

Question 57

The internal structure of the two largest jovian planets (from center outward) is a(an):

A)rocky core with an outer layer of liquid "ices," liquid methane mantle, and a gaseous methane atmosphere.
B)iron-nickel core, rocky mantle, solid crust, and an ocean of liquid "ices."
C)rocky core with an outer layer of liquid "ices," liquid molecular hydrogen layer, and a liquid metallic hydrogen layer.
D)rocky core with an outer layer of liquid "ices," liquid metallic hydrogen layer, and a liquid molecular hydrogen layer.

Question 58

The planet Saturn appears to be:

A)a "sphere," flattened along its polar diameter, significantly more so than for Jupiter.
B)a "sphere," flattened along its polar diameter, considerably less than for Jupiter.
C)a "sphere" in which the equatorial diameter is significantly less than the polar diameter because of the planet's rapid rotation.
D)almost a perfect sphere, with equal polar and equatorial diameters.

Question 59

The distribution of mass inside the planet Saturn is believed to be concentrated more centrally than it is in Jupiter. The most important observation supporting this conclusion is that Saturn:

A)is more massive than Jupiter and is more gravitationally compressed at its center.
B)has a significantly lower density than has Jupiter.
C)is less oblate (flattened) than Jupiter, even though it rotates at approximately the same speed.
D)is more oblate (flattened) then Jupiter, even though it rotates more slowly.

Question 60

No heavy materials (iron, nickel, etc.) have been found in the atmosphere of Jupiter. This is because:

A)they have evaporated away.
B)there were no heavy materials in that part of the solar system where Jupiter was formed.
C)they have sunk to the center.
D)of impacts early in the history of the solar system that ejected these materials to form satellites.

Question 61

The material in the interiors of Jupiter and Saturn thought to be responsible for their powerful magnetic fields is:

A)molten iron and nickel.
B)liquid metallic hydrogen.
C)gases of NH₃ (ammonia), CH₄ (methane), and H₂O (water vapor).
D)solid magnetic iron.

Question 62

Jupiter has a magnetic field that is:

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

Question 63

The source of Jupiter's intense magnetic field is:

A)electric currents in ionized layers of Jupiter's atmosphere.
B)remnant magnetism in Jupiter's rock and iron core.
C)electric currents in Jupiter's liquid hydrogen mantle.
D)electric currents in Jupiter's molten rocky core.

Question 64

Where might you find liquid helium on Jupiter?

A)in the outer core
B)in the mantle
C)in the lower atmosphere
D)nowhere

Question 65

Jupiter subtends an angle of 50 arcsec at opposition. What is the angular size of Jupiter's magnetosphere viewed from Earth at opposition?

A)2 arcmin
B)half a degree
C)4°
D)8°

Question 66

On what planet would you NOT expect to find an aurora?

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

Question 67

Can charged particles from Io affect aurorae on Jupiter?

A)No. Because of the structure of Jupiter's magnetosphere, charged particles from Io cannot reach the upper atmosphere of Jupiter where aurorae form.
B)Yes. The charged particles from Io have the opposite electric charge of those from the Sun and tend to cancel them out. Thus, the aurorae tend to darken.
C)Yes. Charged particles from Io can join charged particles from the Sun and brighten the aurorae.
D)No. Io is too far away to affect the aurorae in the upper atmosphere of Jupiter.

Question 68

Saturn's magnetosphere contains many fewer charged particles than does Jupiter's magnetosphere. Which one of the following is NOT part of the reason for this difference?

A)Saturn has a smaller magnetic field than does Jupiter.
B)Saturn has a much slower rotation rate than Jupiter.
C)Saturn's rings absorb charged particles.
D)Saturn does not have a geologically active satellite within its magnetosphere.

Question 69

Each of the following features is found in association with both Earth and Jupiter, EXCEPT one. Which is the exception?

A)aurorae
B)magnetosphere
C)a charged particle torus
D)large ion belts (called Van Allen belts on Earth)

Question 70

The orbital period of Saturn is about 30 years. What is the time between our "top view" of its rings at maximum tilt and our next observation of this "top view"?

A)15 years
B)30 years
C)60 years
D)The time depends on the difference in directions between Earth's rotation axis and Saturn's rotation axis.

Question 71

Suppose we are viewing Saturn's ring system exactly edge on. How long must we wait until the rings are again edge on? (Assume Saturn's orbital period is 30 years.)

A)a little less than 1 year
B)a little more than 1 year
C)15 years
D)30 years

Question 72

Suppose in a particular year the rings of Saturn are seen exactly edge on from Earth. When will the rings appear from Earth to be exactly face on with the plane of the rings perpendicular to our line of sight? (Assume Saturn's orbital period is 30 years.)

A)7.5 years in the future
B)15 years in the future
C)30 years in the future
D)never

Question 73

What was the nationality of the first person to correctly interpret Galileo's observations of "ears" on Saturn?

A)English
B)American
C)German
D)Dutch

Question 74

The mean thickness of Saturn's rings is now thought to be:

A)a few tens of meters.
B)a few kilometers.
C)a few thousand meters.
D)about 10,000 m.

Question 75

The outer radius of the Saturnian ring system is about 274,000 km, whereas the outer radius of Jupiter's ring system is about 222,000 km. How does the period of the outermost particles in Jupiter's rings compare with the period of the outermost particles in Saturn's rings?

A)For Jupiter the period is about 39% of the period for Saturn.
B)For Jupiter the period is about 73% of the period for Saturn.
C)For Jupiter the period is about 81% of the period for Saturn.
D)For Jupiter the period is about 123% of the period for Saturn.

Question 76

The ring of material that surrounds Jupiter appears to be made up of:

A)pure ice crystals, similar to those in high cirrus clouds on Earth.
B)extremely fine dust particles, about the size of smoke particles, of average diameter 0.001 mm.
C)gas vapor of individual molecules of hydrogen sulfide and sulfur dioxide from Io's volcanoes.
D)icy, reflective rocks, averaging about 1 cm in diameter but with wide variation in size.

Question 77

The origin of the particles that make up Jupiter's rings is believed to be:

A)direct capture from the asteroid belt.
B)remnants of the material that formed Jupiter and its satellites.
C)fragments from meteorite impacts on Metis, Andrastea, Amalthea, and Thebe-the four inner satellites of Jupiter.
D)fragments from meteorite impacts on Io, Europa, Ganymede, and Callisto-the four large satellites of Jupiter.

Question 78

In 1895 James Keeler used the Doppler shift to investigate the motions of Saturn's rings. If you look at the rings edge on, you observe a:

A)Doppler shift that increases as one moves outward from Saturn.
B)Doppler shift that decreases as one moves outward from Saturn.
C)blueshift where the rings cross the body of Saturn, indicating radial motion outward from Saturn.
D)redshift where the rings cross the body of Saturn, indicating radial motion inward toward Saturn.

Question 79

How and by whom was it first determined that the rings of Saturn must be made up of a myriad of small particles, all separately orbiting Saturn in a wide, flat plane?

A)Astronomers at JPL and NASA found from photographs by the Voyager 1 spacecraft that the rings were composed of thousands of tiny ringlets, with particles orbiting even in the Cassini division.
B)Sir George Airy observed that wave-like brightenings propagated through the rings in the direction of rotation, as could be true only if the rings were composed of interacting particles.
C)James Keeler observed that the Doppler shift in reflected sunlight increased inward across the rings, whereas if the rings rotated as a solid body the Doppler shift should increase outward.
D)James Clerk Maxwell calculated that no material could be strong enough to withstand the differential gravitational forces of Saturn on the rings if they were solid.

Question 80

The reason why the individual particles within Saturn's rings have not combined together by mutual gravitational attraction to form one or two moons is that:

A)the gravitational force from the Sun is sufficient to prevent coalescence.
B)tidal distortion forces from the planet are greater than the mutual gravity between the particles.
C)the excess heating from Saturn has melted the ice on the rocks so that the rocks will no longer stick together.
D)they are moving too fast to stick together even if they bump into one another.