Chapter 7 - Astronomy: A Beginner's Guide to the Universe, 7th Edition

Astronomy: A Beginner's Guide to the Universe, 7e (Chaisson/McMillan) Chapter 7 The Jovian Planets: Giants of the Solar System 1) A gravitational assist, or slingshot, can be used to either speed up or slow down a spacecraft. Answer: TRUE Diff: 1 Section Ref.: 7.1 2) All nine planets in the solar system have been visited by spacecraft. Answer: FALSE Diff: 1 Section Ref.: 7.1 3) William Herschel was the discoverer of Uranus. Answer: TRUE Diff: 1 Section Ref.: 7.2 4) Galileo's early telescopes revealed the four large moons of Jupiter, the rings of Saturn, and its large moon Titan. Answer: FALSE Diff: 2 Section Ref.: 7.1 5) While Voyagers were probes that flew past in a few days, Galileo and Cassini are orbiters, designed to study Jupiter and Saturn over prolonged periods of time. Answer: TRUE Diff: 2 Section Ref.: 7.1 6) Most of our detailed knowledge of the jovian planets comes from the Hubble Space Telescope. Answer: FALSE Diff: 2 Section Ref.: 7.1 7) The Galileo probe was deliberately steered into Jupiter's atmosphere, ending its mission. Answer: TRUE Diff: 2 Section Ref.: 7.1 8) When Cassini entered orbit around Saturn, it caused the planet's orbit to change. Answer: TRUE Diff: 3 Section Ref.: 7.1, More Prec. 7.1 9) Like the discovery of Uranus, the finding of Neptune was accidental. Answer: FALSE Diff: 1 Section Ref.: 7.2 10) Changes in the predicted motion of Uranus led to the search for an eighth planet. Answer: TRUE Diff: 2 Section Ref.: 7.2 11) Saturn is less dense than water. Answer: TRUE Diff: 1 Section Ref.: 7.3 12) All four jovian planets are made primarily of hydrogen and oxygen. Answer: FALSE Diff: 1 Section Ref.: 7.3 13) Differential rotation is when a planet's equatorial and polar regions rotate at different rates. Answer: TRUE Diff: 1 Section Ref.: 7.3 14) All four jovian planets spin faster than any of the terrestrials. Answer: TRUE Diff: 2 Section Ref.: 7.3 15) The equators of all four jovian planets rotate more rapidly than the polar regions. Answer: FALSE Diff: 2 Section Ref.: 7.3 16) Jupiter's axial tilt is similar to that of Mercury, while Saturn's is more like ours. Answer: TRUE Diff: 2 Section Ref.: 7.3 17) The rotation of the magnetic fields of the jovian planets is believed to also give us the rotation rate of the planet's core. Answer: TRUE Diff: 2 Section Ref.: 7.3 18) There is a clear relationship between the interior and atmospheric rotation rates of the jovian planets. Answer: FALSE Diff: 2 Section Ref.: 7.3 19) The axial tilts of Uranus and Neptune are similar. Answer: FALSE Diff: 2 Section Ref.: 7.3 20) Jupiter's Great Red Spot is similar to a hurricane on Earth except for its size. Answer: TRUE Diff: 1 Section Ref.: 7.4 21) Jupiter's atmosphere looks uniform and calm, with no visible detail. Answer: FALSE Diff: 1 Section Ref.: 7.4 22) The zonal flows giving rise to the belts and zones are similar to the jet streams in our own stratosphere. Answer: TRUE Diff: 1 Section Ref.: 7.4 23) Although water and ammonia can produce Jupiter's white clouds, the complex coloration we observe in Jupiter's atmosphere requires more complex chemistry. Answer: TRUE Diff: 2 Section Ref.: 7.4 24) The Galileo probe into Jupiter's atmosphere found more water than expected. Answer: FALSE Diff: 2 Section Ref.: 7.4 25) Helium is more abundant on Saturn than on Jupiter. Answer: FALSE Diff: 2 Section Ref.: 7.5 26) Although it is almost the same size as Jupiter, Saturn's gravity is about 2.5 times less, because of Saturn's lower mass and density. Answer: TRUE Diff: 2 Section Ref.: 7.3, 7.5 27) There is less ammonia in the atmospheres of Uranus and Neptune than in Jupiter or Saturn. Answer: TRUE Diff: 2 Section Ref.: 7.5 28) Neptune has a larger fraction of methane in its atmosphere than Uranus. Answer: TRUE Diff: 2 Section Ref.: 7.5 29) The less internal heat a jovian planet emits, the more it stirs up its clouds. Answer: FALSE Diff: 2 Section Ref.: 7.5 30) The Great Dark Spot of Neptune is probably just as long-lived as the more famed Great Red Spot of Jupiter; both lie at about the same latitudes, and are about the same size, relative to their planet. Answer: FALSE Diff: 2 Section Ref.: 7.5 31) Methane absorbs red light readily, so we would expect a planet with a mostly methane atmosphere to appear blue. Answer: TRUE Diff: 3 Section Ref.: 7.5 32) All four jovian planets are oblate, with larger polar than equatorial diameters. Answer: FALSE Diff: 1 Section Ref.: 7.6 33) We have observed a comet strike Jupiter. Answer: TRUE Diff: 1 Section Ref.: 7.6 34) Most of Jupiter's volume is probably in the form of liquid metallic helium. Answer: FALSE Diff: 2 Section Ref.: 7.6 35) In keeping with its Greek god, Neptune probably contains a lot of water, in a slushy mantle ocean. Answer: TRUE Diff: 2 Section Ref.: 7.6 36) Jupiter's magnetic field is much stronger than Earth's, and has a magnetic tail that extends beyond the orbit of Saturn. Answer: TRUE Diff: 2 Section Ref.: 7.6 37) Aurorae like ours have been seen above the poles of Jupiter and Uranus. Answer: FALSE Diff: 2 Section Ref.: 7.6 38) All four Jovian magnetic fields are good examples of the dynamo theory, with the magnetic fields aligned well with the planets' rapid rotations. Answer: FALSE Diff: 2 Section Ref.: 7.6 39) Jupiter puts back into space twice the energy it gets from the Sun. Answer: TRUE Diff: 2 Section Ref.: 7.6 40) Uranus' rotation axis is tipped over 98 degrees, so its magnetosphere is tipped over the same amount. Answer: FALSE Diff: 2 Section Ref.: 7.6 41) Our most detailed knowledge of Uranus and Neptune comes from A) spacecraft exploration. B) the Hubble Space telescope. C) ground-based visual telescopes. D) ground-based radio telescopes. E) manned missions. Answer: A Diff: 1 Section Ref.: 7.1 42) The spacecraft Cassini went into orbit around A) Jupiter. B) Saturn. C) Uranus. D) Neptune. E) Pluto. Answer: B Diff: 1 Section Ref.: 7.1 43) The Galileo mission put a spacecraft into orbit around Jupiter. Which statement is true? A) The spacecraft crashed into the moon Europa. B) The spacecraft used a gravity assist from both Venus and Earth. C) A saltwater ocean was discovered on Jupiter. D) Intense magnetic fields were discovered in the asteroid belt. E) A probe was released which soft landed on Io. Answer: B Diff: 2 Section Ref.: 7.1 44) Which three played a role in the finding of Neptune? A) Herschel, Hubble, and Einstein B) Newton, Einstein, and Tombaugh C) Adams, Leverrier, and Galle D) Bode, Herschel, and Fraunhofer E) Shapley, Hubble, and Whipple Answer: C Diff: 2 Section Ref.: 7.2 45) Small deviations in a planet's orbital motion A) show we don't fully understand gravitational forces yet. B) indicate the presence of an extensive atmosphere. C) indicate the presence of a powerful magnetic field. D) imply the nearby presence of a massive body. E) show the planet's orbit isn't stable. Answer: D Diff: 2 Section Ref.: 7.2 46) Adams and Leverrier both predicted the position of Neptune, based on its effects on A) the Sun. B) Jupiter. C) Saturn. D) Uranus. E) Pluto. Answer: D Diff: 2 Section Ref.: 7.2 47) Uranus was discovered A) by Galileo. B) thousands of years ago. C) with a radio telescope. D) after examining perturbations in Neptune's orbit. E) less than 250 years ago. Answer: E Diff: 2 Section Ref.: 7.2 48) At which planet can the pole remain in darkness for 42 years, then have 42 years of constant daylight? A) Jupiter B) Saturn C) Uranus D) Neptune E) Pluto Answer: C Diff: 1 Section Ref.: 7.3 49) In terms of axial tilt, which of the jovian planets shows us the largest inclination? A) Jupiter B) Saturn C) Uranus D) Neptune E) Pluto Answer: C Diff: 1 Section Ref.: 7.3 50) If you could find a bathtub big enough for Saturn, the planet would A) precipitate more helium. B) float. C) explode due to its liquid metallic hydrogen. D) catch fire, as liquid sodium reacts with water. E) sink due to its metallic interior. Answer: B Diff: 1 Section Ref.: 7.3 51) The planet whose pole was facing the Sun when Voyager 2 approached in 1986 was A) Jupiter. B) Saturn. C) Uranus. D) Neptune. E) Mars. Answer: C Diff: 1 Section Ref.: 7.3 52) Jupiter and the other jovian planets are noticeably oblate because A) they all have strong magnetic fields that deform their shape. B) their powerful gravity acts stronger on the closer poles than the distant equator. C) they are fluid bodies that are spinning rapidly. D) they are tidally distorted by the pulls for their satellite systems. E) All of the above are correct. Answer: C Diff: 2 Section Ref.: 7.3 53) Cometary impacts with Jupiter A) are impossible to observe from Earth. B) have been observed from Earth at least twice. C) are extremely rare. D) are spectacular but do not teach us much. E) would not be catastrophic if they happened on Earth. Answer: B Diff: 2 Section Ref.: Discovery 7.2 54) Which of these is true about the seasons of Uranus? A) With a tilt of 29 degrees, they are not that different from our solstices and equinoxes. B) Its strange tilt produces extreme seasonal variations, especially at the poles. C) At the Uranian equator, the Sun would pass overhead every sixteen hours. D) At the Uranian pole the Sun sets every 16 hours during the summer and winter. E) There are no seasons at the poles. Answer: B Diff: 2 Section Ref.: 7.3 55) The reason the jovian planets lost very little of their original atmosphere is due to their A) rapid rotation. B) strong magnetic fields. C) ring systems. D) large mass. E) many moons. Answer: D Diff: 2 Section Ref.: 7.3 56) Compared to Saturn, Jupiter is about A) half as massive and denser. B) three times more massive and denser. C) 100 times more massive. D) twice the diameter, but less dense. E) half as dense, but the same mass since it is larger. Answer: B Diff: 2 Section Ref.: 7.3 57) Studying the magnetospheres of the jovian planets has allowed us to measure their A) interior rotation rates. B) orbital periods. C) orbital radius. D) gravity. E) ring system diameters. Answer: A Diff: 2 Section Ref.: 7.3 58) Essentially, the Great Red Spot is A) Neptune's largest atmospheric feature. B) a large cyclonic storm (hurricane). C) always located within 10 degrees of Jupiter's north pole. D) composed primarily of iron oxide. E) traveling north and south across Jupiter's face. Answer: B Diff: 1 Section Ref.: 7.4 59) Alternating zones of rising and sinking gas in Jupiter's atmosphere A) create light and dark bands. B) cause Jupiter's magnetic field to ripple. C) produced the ring system discovered by Voyager. D) generate magnetic fields. E) circle the planet from pole to pole. Answer: A Diff: 3 Section Ref.: 7.4 60) The only probe into the atmospheres of any jovian planet was launched by A) Voyager 2 into Titan's atmosphere. B) Pathfinder into Mars' atmosphere. C) Cassini into Saturn's clouds. D) Galileo into Jupiter's equatorial zone. E) Huygens into Saturn's equatorial belt. Answer: D Diff: 3 Section Ref.: 7.4 61) The two outer jovian planets appear bluish in color because A) methane gas in their atmospheres absorbs red light well. B) ammonia absorbs blue light well. C) hydrogen and helium are both blue in large concentrations. D) dust motes in their atmospheres scatter blue well, just as in our own blue sky. E) from their distance, the Sun would appear hotter and bluer than from Earth. Answer: A Diff: 1 Section Ref.: 7.5 62) Which common gas is less abundant in the top of Saturn's atmosphere, compared to what we observe at Jupiter? A) hydrogen B) helium C) nitrogen D) methane E) argon Answer: B Diff: 2 Section Ref.: 7.5 63) Why does Saturn radiate even more excess heat than Jupiter? A) Only Saturn is still radiating heat left over from its formation. B) Saturn's thick clouds give it a stronger greenhouse effect. C) Helium rain falling inward generates heat as it descends. D) Saturn's atmosphere contains much methane, which is very flammable. E) Saturn is more massive than Jupiter, so its gravitational compression is stronger. Answer: C Diff: 2 Section Ref.: 7.6 64) Which planet had the Great Dark Spot in 1989, but had lost it by 1995? A) Jupiter B) Saturn C) Uranus D) Neptune E) Mars Answer: D Diff: 2 Section Ref.: 7.5 65) Of the jovian planets, which generates the least internal heat? A) Jupiter B) Saturn C) Uranus D) Neptune E) Pluto Answer: C Diff: 2 Section Ref.: 7.6 66) The magnetic field tilts of which two bodies are the most unusual? A) Mercury and Earth B) Jupiter and Saturn C) Uranus and Neptune D) Saturn and Pluto E) Mars and Saturn Answer: C Diff: 2 Section Ref.: 7.6 67) What is the source of Jupiter's intense radio waves and magnetism? A) charged particles trapped in Jupiter's solid iron core similar to Earth B) liquid metallic hydrogen swirling in the rapidly spinning mantle C) the ionized sulfur ejected into a torus around Jupiter by Io D) the auroral displays in the polar regions, just like with Earth E) a liquid iron and nickel outer core, just like Earth's magnetic field Answer: B Diff: 2 Section Ref.: 7.6 68) Jupiter gives back into space twice the energy it gets from the distant Sun. Where is this energy coming from, for the most part? A) the impact energy of comets like SL-9 B) helium rain descending into its mantle and core C) the slow escape of gravitational energy left from its formation D) the radioactive decay of U-238 in its iron-rich core, just as with the Earth E) the combined tidal stress of all four large Galilean moons Answer: C Diff: 2 Section Ref.: 7.6 69) What is true of Jupiter's magnetosphere? A) Although its surface field is greater, since the planet is larger the total field is actually weaker than Earth's. B) It does not trap protons and electrons, as Earth's Van Allen belts do. C) It has a tail that extends at least to Saturn's orbit. D) It is most extensive on the sunward side of the planet. E) It is only slightly stronger than Saturn's. Answer: C Diff: 2 Section Ref.: 7.6 70) What is thought to lie at the center of Jupiter? A) a hot sea of liquid metallic hydrogen B) a solid core of crystalline helium C) a massive core of rocky materials with some iron mixed in D) gaseous hydrogen and helium, for Jupiter is not differentiated like Earth E) a fusion core like the Sun's, with hydrogen being turned into helium Answer: C Diff: 2 Section Ref.: 7.6 71) Which two jovian planets have magnetic field tilts that are not along their rotation poles? A) Jupiter and Saturn B) Jupiter and Uranus C) Saturn and Neptune D) Uranus and Neptune E) All jovian planets have magnetic fields close to their rotational axes. Answer: D Diff: 2 Section Ref.: 7.6 72) In brightness, Jupiter is second only to the planet ________ most of the time. Answer: Venus Diff: 1 Section Ref.: 7.1 73) In the telescope, ________ shows the most turbulent atmosphere, with changes easily seen even with amateur telescopes. Answer: Jupiter Diff: 1 Section Ref.: 7.1 74) The most famous and long lasting storm in the solar system is ________. Answer: (Jupiter's) Great Red Spot Diff: 1 Section Ref.: 7.1 75) Jupiter is largest and brightest in our skies when seen at ________. Answer: opposition Diff: 2 Section Ref.: 7.1 76) A "gravitational slingshot" enables a spacecraft to ________. Answer: speed up, or slow down, or change direction. Diff: 2 Section Ref.: 7.1 77) Adams and Leverrier predicted the position of ________, which Galle confirmed. Answer: Neptune Diff: 1 Section Ref.: 7.2 78) William Herschel discovered the green disk of ________ as the first telescopic planet. Answer: Uranus Diff: 1 Section Ref.: 7.2 79) While Saturn is almost as large as Jupiter, its mass is only about ________ of Jupiter's. Answer: one-third Diff: 1 Section Ref.: 7.3 80) The oblateness of the jovian planets' disks is caused by their ________. Answer: rapid rotations Diff: 1 Section Ref.: 7.3 81) Compared to the terrestrial planets, the jovian planets have ________ average densities. Answer: low. Diff: 1 Section Ref.: 7.3 82) Of the planets, ________ is the least dense, and could float on water. Answer: Saturn Diff: 1 Section Ref.: 7.3 83) The oblateness of the jovian planets' disks refers to their ________ equatorial diameters, compared to the polar diameters. Answer: larger Diff: 1 Section Ref.: 7.3 84) Like Jupiter's, Saturn's rotation is fast and differential, with the ________ rotating fastest. Answer: equator Diff: 1 Section Ref.: 7.3 85) Unlike Jupiter and Saturn, at Uranus and Neptune the ________ rotates the slowest. Answer: equator Diff: 2 Section Ref.: 7.3 86) In general, wind direction ________ between adjacent bands in Jupiter's atmosphere. Answer: alternates Diff: 2 Section Ref.: 7.4 87) Jupiter's bright zones are cloud streams made of ________ ice crystals. Answer: ammonia Diff: 1 Section Ref.: 7.4 88) Jupiter's darker ________ are complex in color and origin, with complex organic molecules including carbon, sulfur, and nitrogen. Answer: belts Diff: 1 Section Ref.: 7.4 89) The Great ________ Spot of Neptune was striking in 1989, but gone by 1995. Answer: Dark Diff: 1 Section Ref.: 7.5 90) Uranus and ________ are very similar in size, mass, and color. Answer: Neptune Diff: 1 Section Ref.: 7.5 91) The most abundant molecule in Saturn's atmosphere is ________. Answer: hydrogen. Diff: 1 Section Ref.: 7.5 92) ________ looked very bland in Voyager 2 photos in 1986, but as equinox approached in the 1990s, its disk showed belts, zones, and storms. Answer: Uranus Diff: 1 Section Ref.: 7.5 93) The white zones of Jupiter and Saturn are made of ________ ice, apparently dissolved in the deep oceans of Uranus and Neptune. Answer: ammonia Diff: 1 Section Ref.: 7.5 94) Because it has a higher percentage of ________, Neptune appears even bluer than Uranus. Answer: methane Diff: 1 Section Ref.: 7.5 95) Methane gas absorbs the color ________, accounting for the colors of Uranus and Neptune. Answer: red Diff: 2 Section Ref.: 7.5 96) Compared to Jupiter, the element ________ is notably less common in Saturn's atmosphere, perhaps condensing to fall toward the core as rain. Answer: helium Diff: 2 Section Ref.: 7.5 97) Compared to Jupiter, Saturn's east-west zonal (band) flow is ________. Answer: more stable or faster. Diff: 2 Section Ref.: 7.5 98) While the mantles of Jupiter and Saturn are made of liquid metallic hydrogen, the mantles of Uranus and Neptune are chiefly ________. Answer: water (and ice) Diff: 1 Section Ref.: 7.6 99) Jupiter radiates twice as much energy as it receives from solar light; the source of this "excess" energy is ________. Answer: gravitational contraction Diff: 1 Section Ref.: 7.6 100) While ________ rotation axis is only tilted 29 degrees, its magnetic fields are just as strange as its twin's. Answer: Neptune's Diff: 1 Section Ref.: 7.6 101) Their magnetic fields should originate in the planets' ________, but those of Uranus and Neptune don't even come close. Answer: cores Diff: 1 Section Ref.: 7.6 102) Jupiter's magnetic field is produced in its rapidly spinning mantle of ________. Answer: liquid metallic hydrogen Diff: 2 Section Ref.: 7.6 103) How are Jupiter and Saturn similar? Answer: Both are about the same size, with oblate disks due to rapid rotation, striped with white zones and brownish belts. Diff: 1 Section Ref.: 7.1 104) Name two space probes to the jovian planets and their destinations. Answer: Voyager I to Jupiter and Saturn, Voyager 2 to all four jovians, Galileo to Jupiter, Cassini to Saturn. Diff: 1 Section Ref.: 7.1 105) Contrast the destinations of the probes dispatched by the Galileo and Cassini missions. Answer: Galileo's probe fell into the atmosphere of Jupiter, soon to be destroyed by heat and pressure. Cassini's probe, built by the ESA, was sent into the atmosphere of Saturn's moon, Titan. Diff: 1 Section Ref.: 7.1 106) Describe how the motion of Uranus led to the discovery of Neptune. Answer: Uranus at first was moving faster than predicted, then after 1822 mysteriously slowed down, as it had passed Neptune and was now pulled back by Neptune's gravity. Adams and Leverrier used this perturbation to predict the position of Neptune, which Galle used to telescopically locate its blue disk. Diff: 3 Section Ref.: 7.2 107) Contrast the rotation rates of the jovian planets with the terrestrial planets. Answer: All four jovian planets have a much faster rotation rate than any of the Terrestrial planets. Diff: 1 Section Ref.: 7.3 108) Contrast the differential rotations of the four jovian planets. Explain. Answer: At Jupiter and Saturn, the equators rotate the fastest, but at Uranus and Neptune, the higher latitudes rotate faster than the equator. We do not yet understand this. Diff: 3 Section Ref.: 7.3 109) Uranus and Neptune are often called twin worlds. How do their axial tilts differ? Answer: At 98 degrees, Uranus is flopped over on its side, and can have its pole pointing directly at the Sun, as it did when Voyager 2 passed it in 1986. Neptune's tilt is a more normal 29 degrees. Diff: 3 Section Ref.: 7.3 110) What element is notably deficient in Saturn's atmosphere, and why? Answer: Helium seems to be condensing and raining downward toward Saturn's mantle. Diff: 2 Section Ref.: 7.5 111) What common gas assumes an uncommon state in the mantles of Jupiter and Saturn? Why? Answer: Hydrogen. On Earth hydrogen is a gas because of the pressure and temperature in our atmosphere. On Jupiter and Saturn, it can be liquid and have the properties of a metal because of the much higher temperatures and pressures. Diff: 2 Section Ref.: 7.6 112) In what ways are the magnetic fields of Uranus and Neptune unusual? Answer: Unlike the magnetic fields of Earth, Jupiter, and Saturn, the fields of Uranus and Neptune are not aligned with the rotational axis of their planet. Additionally, both fields are offset from their planet's center by a significant amount. Diff: 3 Section Ref.: 7.6 113) Why do Uranus and Neptune appear bluish? Answer: Methane absorbs red light, and is common in their atmospheres. Diff: 3 Section Ref.: 7.6 114) Compare and contrast the Galileo and Cassini missions. Answer: Both are orbiters of jovian planets, but the probe for Galileo fell into Jupiter's atmosphere, while the Huygens probe from Cassini was sent to Saturn's large moon Titan. Both used a gravitational slingshot via Earth and Venus to reach their destinations, resulting in reduced fuel consumption and possibly a longer than expected useful life. Cassini was able to collect data on Jupiter as it flew past. Diff: 2 Section Ref.: 7.1 115) Why was Voyager 2 an extremely efficient and productive probe? Answer: Using gravitational assists, Voyager 2 was able to visit all four jovian planets, making many discoveries along the way. In effect, one spacecraft performed the equivalent of four missions. Diff: 2 Section Ref.: 7.1 116) Compare the differential rotation rates of the four jovian planets. Answer: Jupiter and Saturn rotate rapidly, in about ten hours, with their equators spinning fastest. Both Uranus and Neptune spin slower (but still faster than Earth), and their equators spin slower than their higher latitudes. Diff: 2 Section Ref.: 7.3 117) Discuss the seasons of Uranus. Answer: Flopped over with a 98 degree tilt, Uranus' pole was pointing toward the Sun at solstice in 1986 when Voyager 2 flew past. With one hemisphere in constant daylight, the atmosphere was very bland. But by equinox in 2008, the whole planet was receiving eight hours of day and night, and the heating patterns were producing more normal jovian belts and zones. At each pole, you would get 42 years of constant Sun, then 42 years of darkness. Diff: 2 Section Ref.: 7.3 118) How might the odd tilt of Uranus have been produced? Answer: As with the making of our Moon and Earth's axial tilt, a large impact is possibly the factor that flipped Uranus over on its side. Diff: 2 Section Ref.: 7.3 119) Contrast the compositions of Jupiter's belts and zones. Answer: The zones are high, cold regions of ammonia ice crystals, white in color. But the lower, warmer belts are brownish from complex chemistry involving hydrogen sulfide, ammonia, and other chemicals. Diff: 2 Section Ref.: 7.4 120) Discuss the roles that ammonia, hydrogen sulfide, and methane play in the appearances of the jovian planets. Answer: White ammonia ice makes up the zones of Jupiter and Saturn, and combines with hydrogen sulfide and other chemicals to make up the brownish belts. But it is not as common at Uranus and Neptune, perhaps instead dissolved in their water mantles. At Uranus and Neptune, methane is the chief coloring agent, absorbing red light strongly, and reflecting the blue light back into space. Diff: 2 Section Ref.: 7.5 121) Name two ways the magnetic fields of Uranus and Neptune defy the normal behavior of planetary magnetic fields. Answer: Their fields are tilted very far off the rotation axes of both planets; most other planets have fields within 10 degrees of their poles. Neither field goes directly through the core of its planet, while all other fields seem to originate in the cores of their planets. Diff: 2 Section Ref.: 7.6 122) Contrast the Great Red and Great Dark Spots. Answer: Both storms are oval, and lie at mid-southern latitudes. But Jupiter's Great Red Spot has been continuously observed since we had telescopes that could spot it, while the Great Dark Spot was prominent for Voyager 2 in 1989, but had vanished from the disk of Neptune by 1995. Diff: 3 Section Ref.: 7.6 123) Describe the interaction between Jupiter and Comet Shoemaker-Levy 9. Answer: When the comet passed close to Jupiter in 1992, gravitational tidal forces tore the nucleus apart, leaving it in fragments. On its approach in 1994, it struck the planet. Vibrations in the interior and atmospheric effects lasted for days. Huge fireballs were observed from Earth. Debris from the comet spread completely around the planet, taking years to settle out. Diff: 3 Section Ref.: 7.6, Disc. 7.1 1 Copyright © 2013 Education, Inc.