sign in sign up
<<
Home , Amor asteroid, Apollo asteroid, Charon, Kirkwood gap, Small Solar System body

1. Some of the definitions of the different types of objects in has the greatest orbital inclination ( at the the overlap. Which one of the greatest angle to that of )? following pairs does not overlap? That is, if an A) object can be described by one of the labels, it B) cannot be described by the other. C) A) dwarf and D) B) and object C) satellite and Kuiper belt object D) and planet 10. Of the following objects in the solar system, which one has the greatest and therefore the most elliptical orbit? 2. Which one of the following is a ? A) Mercury A) , a of B) Mars B) Pluto C) Earth C) (an asteroid) D) Pluto D) Mathilde (an asteroid)

11. What is the largest moon of the dwarf planet Pluto 3. Which of the following objects was discovered in the called? twentieth century? A) A) Pluto B) B) C) C) D) D) Ceres

12. If you were standing on Pluto, how often would you see 4. Pluto was discovered in the satellite Charon rise above the horizon each A) 1930. day? B) 1846. A) once each 6-hour day as Pluto rotates on its axis C) 1609. B) twice each 6-hour day because Charon is in a retrograde D) 1781. orbit C) once every 2 days because Charon in the same direction Pluto rotates but more slowly 5. How was the dwarf planet Pluto discovered? D) never—Charon is a synchronous satellite with an orbital A) by prediction using Newton's laws to account for the period exactly equal to Pluto's rotation period deviations from uniform orbits of Uranus and Neptune B) by the infrared cameras on the IRAS spacecraft 13. Earth's Moon subtends an angle of about 0.5° when C) by Voyager spacecraft cameras, which were used between viewed from Earth. Charon is about 1200 km in planetary encounters to survey the planetary diameter and about 18,490 km away from the system surface of Pluto. How large an angle does it D) by searching photographs of the sky for an object that subtend when viewed from Pluto? moved against the background of distant stars A) about the same size angle as Earth's Moon B) about 7 times larger an angle than Earth's Moon C) about 11 times larger an angle than Earth's Moon 6. Pluto is believed to have D) over 100 times larger an angle than Earth's Moon A) no atmosphere at all. B) a thick atmosphere of carbon dioxide. C) a thin atmosphere of water vapor. 14. What technique has allowed scientists to determine the D) a thin atmosphere containing some nitrogen. relative sizes of Pluto and Charon? A) imaging by the Voyager spacecraft in 1989 B) direct photography using adaptive-optics telescopes on 7. Which of the following objects was farthest from the Earth in 1995 in 1990? C) of this planet by Earth's Moon during the A) Pluto 1980s B) Charon D) eclipses of the planet's surface by its moon, Charon, C) Neptune during 1985–1990, viewed from Earth D) Uranus

15. What is unique about the Pluto-Charon system, compared 8. Which planet or dwarf planet in our solar system has the with all other in the solar system? moon with the largest diameter compared with the A) Both Pluto and Charon are volcanically active, with lava diameter of the planet or dwarf planet itself? flows and vents of sulfur dioxide gas. A) Earth B) Charon is an icy moon, but it is in orbit around a giant B) Saturn planet made mostly of liquid . C) Neptune C) Pluto has only one satellite. D) Pluto D) Both Pluto and Charon are in synchronous rotation, so each object maintains the same face toward the other object at all times. 9. Of the following objects in the solar system, which one B) Gaspra 16. The Pluto-Charon system moves in which way in its C) Ceres mutual motion? D) A) Charon orbits Pluto with exactly Pluto's rotation period. B) Charon orbits Pluto once while Pluto rotates twice. C) There is no relationship between rotation period of Pluto 24. The size of the largest asteroid, Ceres, compared with the and of Charon. largest mare or impact basin on the Moon, Mare D) Charon orbits Pluto twice while Pluto rotates once. Imbrium, is A) not comparable because all are very small objects (1 km diameter), whereas most maria 17. Based on its mean density, the dwarf planet Pluto is are large (100–1000 km diameter). A) similar to the Jovian planets in composition, although it is B) much smaller, only about 1/3 the size. much smaller in size. C) very similar, about 1000 km across. B) similar to the terrestrial planets in composition, although D) much larger, by a factor of more than 2. it is much smaller in size. C) similar to the terrestrial planets in composition, although it is much larger in size. 25. What is the diameter of the largest asteroid in the solar D) a real oddity, denser than the Jovian planets but lighter system, Ceres, compared with the diameter of than the terrestrial planets. Earth, which is about 12,800 km? A) smaller than 1/100 Earth's diameter B) less than 1/10 Earth's diameter 18. Based on its mean density, the dwarf planet Pluto appears C) about 1/4 Earth's diameter to be composed of D) about 1/2 Earth's diameter A) rock and iron. B) a mixture of rock and ice. C) gases such as methane and ammonia, possibly with a 26. When compared with the diameter of Earth's Moon, the small, liquid core. diameters of the biggest asteroids are D) the very lightest elements, hydrogen and helium. A) very much smaller (less than 1/10). B) about the same size. C) very much larger, by a factor of at least 5. 19. The first satellite discovered in orbit about Pluto was D) between 1/10 and 1/3 as large. Charon. What is unusual about this moon? A) Charon is the only moon in the solar system known to have an atmosphere. 27. If all the material in the were to be B) Charon is much warmer than it should be, given its combined to produce a planet, how big would it be? position in the solar system. A) about 1500 km in diameter, less than half the diameter of C) Compared with planet-satellite systems in the rest of the the Moon solar system, Charon is very large and very B) only a few kilometers in diameter, similar to an average close to Pluto. mountain on Earth D) Charon is geologically active. C) about the size of Earth, with a diameter of about 13,000 km. D) about the size of Mercury, with a diameter of about 5000 20. Which solar system object was found on January 1, 1801, km. located between the orbits of Mars and Jupiter? A) asteroid Ceres B) Halley's 28. A few of the largest asteroids appear to be spherical. C) Kuiper belt object 1993 SC How do you think they got this way? D) asteroid Gaspra A) The visible outer atmospheres of these large asteroids are spherical even though the underlying surfaces are irregular. 21. Who was the first person to discover an asteroid? B) The largest asteroids solidified from spherical gas clouds A) German astronomer Johann Bode in their early history and retained this shape. B) English astronomer Sir William Herschel C) Repeated collisions with other asteroids have worn the C) German mathematician Karl Friedrich Gauss largest asteroids down to spheres. D) Italian astronomer Guiseppe Piazzi D) Self-gravity was sufficient to pull the largest asteroids into a spherical shape during their early history. 22. On New Year's Day, 1801, Giuseppe Piazzi discovered the asteroid Ceres. His search was inspired by an event that had occurred only about twenty years 29. Unlike the other dwarf planets in the Kuiper belt, before. What was the event? has no . Is this significant? A) first astronomical use of the telescope by Galileo A) No. Having or not having a moon does not really make a B) invention of the first practical reflecting telescope by significant difference. Newton B) Yes. It indicates that Makemake is older than the others. C) discovery of Uranus by Herschel C) Yes. It indicates that Makemake is younger than the D) discovery of Pluto by Tombaugh others. D) Yes. It means that it is harder to determine the mass of Makemake. 23. What is the largest known asteroid in our solar system? A) 30. An asteroid is charted, with a redshifted solar spectrum of A) a small, easily recognizable group of stars within a reflected light. constellation. B) The asteroid would appear as a short trail against the B) a moving in an orbit around the Sun. background stars on a sky-tracked long- C) another name for the nucleus of a comet, a volatile object exposure photograph, and its spectrum would that moves around the Sun in a long, show no Doppler shift. elliptical orbit. C) The asteroid would appear as a slowly brightening point D) a before it enters the atmosphere and plunges to of light where no star had previously been Earth. charted, and the spectrum of sunlight reflected from it would be blueshifted by the Doppler effect. 31. The asteroid belt exists between the orbits of the planets D) The asteroid would appear as a slowly brightening and A) Earth and Mars. growing diffuse sphere of light where no star B) Jupiter and Saturn. was charted because of light scattered from C) and Earth. the dust and gas surrounding it, and it would D) Mars and Jupiter. show a blueshifted spectrum.

32. Most of the asteroids of the solar system move around 38. The number of known asteroids rose sharply in the the Sun between the orbits of which planets? 1890s. What was the cause of this? A) Earth and Mars A) The technique of astrophotography was introduced. B) Jupiter and Saturn B) The first very large telescopes were built. C) Venus and Earth C) Better theoretical predictions of where to look for D) Mars and Jupiter asteroids became available. D) A series of collisions involving large objects between the orbits of Mars and Jupiter resulted in many 33. Which of the following statements about asteroids is more asteroids being formed. NOT true? A) Only a minority of all asteroids are in the asteroid belt. B) Some asteroids have orbits that carry them inside Earth's 39. By 1891 only about 300 asteroids had been discovered. orbit. After 1891 hundreds more were discovered quickly. C) Some asteroids occupy the same orbit as Jupiter. What caused this increased discovery rate for D) The total mass of all asteroids is much smaller than the asteroids? mass of Earth. A) invention of the telescope B) invention of photography C) advent of astrophotography 34. The number of asteroids with diameters greater than 100 D) heightened interest in the solar system fueled by Percival km is Lowell and the Martian canals controversy A) just over 1000. B) 3. C) about 30. 40. The average sidereal period for an asteroid moving D) about 230. around the Sun in the asteroid belt, according to Kepler's law, is A) 46.8 years. 35. The total number of asteroids orbiting the Sun among the B) 2.8 years. planets is estimated to be C) 4.68 years. A) several thousand. D) 1.99 years. B) hundreds of billions. C) more than a million. D) a few hundred. 41. If an asteroid were to be moving in a circular orbit around the Sun with an orbital period of 1/5 that of Jupiter, what would be the radius of its orbit? 36. How would a typical asteroid appear on a time exposure A) 1.78 AU photograph of the sky as it orbited the Sun if the B) 15.2 AU camera were tracking the background stars? C) 1.04 AU A) The asteroid would look like a star, a small extra dot not D) 3.65 AU shown on star charts of this area of the sky. B) The asteroid would look like a small, diffuse patch against the sharp images of stars because of 42. The asteroid belt is believed by most astronomers to be the dust and gas surrounding it. composed of C) The asteroid would produce a flash of light as it crossed A) rocky debris left over from the formation of the solar the field of view of the camera. system. D) The asteroid would produce a short trail as it moved B) genuine leather. slowly against the background stars. C) rather dirty ice balls similar to the nuclei of . D) the remnants of a gaseous planet disrupted by a massive impact. 37. How would we be able to detect a large asteroid if it were heading straight for Earth? A) The asteroid would appear as a slowly brightening 43. Computer simulations of the formation of the solar starlike object where no star was previously system show that the material in the vicinity of the asteroid belt is not in the form of one large planet 48. Jupiter's orbital period is approximately 12 years. Based because on this number, you would be most likely to find an A) most of the material originally in the asteroid belt crashed asteroid belt asteroid with a period of how many into Mars, creating the heavily cratered years? terrain we see there. A) 4 B) a violent collision destroyed two protoplanets, the debris B) 6 from which became the asteroid belt. C) 7.3 C) this region is where the gravitational field of the Sun is D) 24 balanced by that of Jupiter, preventing coalescence of matter into a planet. D) Jupiter's gravitational pull flung most of the material in 49. What effect does Jupiter have on asteroids in the asteroid this region out of the solar system and belt? prevented coalescence of the rest. A) Jupiter has no effect whatever on such small objects because they are a long way away from Jupiter, and Jupiter's gravitational influence 44. Why does no major planet orbit the Sun at the location of varies as the inverse square of distance, by the asteroid belt? Newton's law. A) One such object did form there but was destroyed by a B) Jupiter perturbs only the orbits of asteroids whose orbital collision with an early comet; the asteroid periods are a simple fraction (e.g., 1/2, 1/3, belt is the debris from the collision. 2/3, 2/7) of its orbital period. B) Jupiter's gravitational pull stirred up the , C) Jupiter disturbs only the orbits of asteroids whose orbital preventing them from coalescing into a single distances (or semimajor axes) are a simple large object. fraction (e.g., 1/2, 1/3, 2/3, 2/7) of the radius C) In the early solar nebula, the temperature that close to the of Jupiter's orbit. Sun was too high for rock or iron to condense D) Jupiter disturbs the orbits of all the asteroids in the belt, into solid form. slowing them down and causing them to D) Three Earth-sized planets did form there, but they spiral slowly in toward the Sun. destroyed each other by mutual collisions; the asteroid belt is the debris from these collisions. 50. What is the relationship between the Kirkwood gaps in the asteroid belt and the Cassini division in the ? 45. Which one of the following statements about the asteroid A) Both the Kirkwood gaps and the Cassini division are belt is false? caused by large objects passing through A) The masses of all the known asteroid belt asteroids, added swarms of smaller objects, sweeping out gaps together, would produce a body too small to in the swarms. be classified as a planet. B) Both the Kirkwood gaps and the Cassini division were B) All known asteroids orbit between Mars and Jupiter. discovered by observers from the same C) In spite of the vast average separations between asteroids, group; Kirkwood and Cassini both worked at they can sometimes collide. the same observatory. D) Almost all asteroids have orbits that lie near the plane of C) Both the Kirkwood gaps and the Cassini division are the ecliptic. caused by disruptions of the orbits of small objects by larger planets or moons. In both cases, the orbital distance of small objects in 46. The Kirkwood gaps (see Figure 9-10, Comins and the gaps is related by simple fractions to the Kaufmann, Discovering the , 9th ed.) are orbital distance to the disturbing object. in the D) Both the Kirkwood gaps and the Cassini division are A) asteroid belt at places where there are very few asteroids. caused by disruptions of the orbits of small B) rings of Saturn, where there is less material than at other objects by larger planets or moons. In both radii. cases, the periods of the small objects are C) spectrum of hydrogen gas, where light has been absorbed simple fractions of those of the larger by molecules first identified by Kirkwood. disturbing object. D) equatorial region of the Sun, where no sunspots are found. 51. The asteroid belt has a gap where few objects are found because of repeated gravitational disturbances from 47. The Kirkwood gaps are caused by Jupiter. At what distance from the Sun will this gap A) large asteroids moving in circular orbits within the be found if objects in the gap have a period one asteroid belt, which sweep out and collect third that of Jupiter? (Hint: Use Kepler's law.) smaller objects in their path. A) 7.86 AU B) large asteroids whose orbits carry them periodically B) 3.28 AU through the asteroid belt, where they sweep C) 2.5 AU out a path and leave it devoid of asteroids. D) 2.6 AU C) the gravitational pull of Jupiter, which nudges asteroids into new orbits. D) large asteroids on the outer fringe of the asteroid belt, 52. Jupiter's orbital period is approximately 12 years. If it which gravitationally affect the paths of were exactly 12 years, which of the following smaller objects within the belt. periods would NOT produce an effective resonance with Jupiter? A) 3.0 years B) 6.0 years B) Jupiter; only Jupiter is massive enough to produce a C) 5.1 years Lagrange point D) 8.0 years C) Jupiter and the planets beyond it; a Lagrange point must be a certain distance from its planet, and only the orbits of Jupiter and the planets beyond it 53. What is the typical distance between asteroids in the are large enough to accommodate a Lagrange asteroid belt? point A) 6000 km D) only the planets with moons B) 1.2 AU C) 25 km D) 10 million km 60. Why is the star Zeta Leporis, in Lepus the Hare, an object of particular interest? A) Zeta Leporis is still in the nebular stage; it is only a few 54. What is the average distance between asteroids? hundred million years old. A) about three times the length of a football field B) Zeta Leporis appears to have an Earthlike planet. B) about twice the diameter of Earth C) Zeta Leporis is believed to have passed near the Sun early C) about half the distance between Earth and the Moon in the history of the solar system, causing D) many times the distance between Earth and the Moon gravitational disruptions that affect the orbits of the asteroids. D) Zeta Leporis appears to have an asteroid belt of its own. 55. How are space probes to the outer planets such as Jupiter protected from being obliterated by collisions with asteroids in the asteroid belt? 61. all of the following characteristics have been observed in A) They aren't. We lose only one out of every four spacecraft asteroids except one. Which one is the exception? to collisions with asteroids, so it is cheaper to A) regolith take our chances. B) craters B) The spacecraft are equipped with cameras to detect C) satellites asteroids so that they can be directed safely D) magnetic field around them. C) The spacecraft are sent in an inclined orbit that arcs above or below the asteroid belt, then crosses the 62. Asteroids that orbit the Sun in the stable Lagrange points ecliptic again near Jupiter. in Jupiter's orbit are known as D) They aren't. Asteroids are so far apart that the spacecraft A) adenoids. just sail through. B) asteroids. C) Trojans. D) Jupitoids. 56. What is a Hirayama family of asteroids? A) group of asteroids that have identical orbits B) either of two groups of asteroids that orbit at Jupiter's 63. The collection of asteroids trapped at Jupiter's distance from the Sun Lagrange points was C) group of asteroids that have identical spectra and A) a surprise when first discovered by the 5-meter Mount therefore identical compositions Palomar telescope. D) group of asteroids that have orbits that cross Earth's orbit B) a surprise when first discovered by the Hubble Space but remain outside Venus's orbit Telescope. C) a surprise when first discovered by the Voyager 2 mission. 57. What is unusual about the asteroid Karin? D) predicted by the mathematician Lagrange in 1772. A) Karin is the that comes closest to Earth. B) Karin was the first of the Trojan asteroids to be discovered. 64. Where do the Trojan asteroids orbit the Sun? C) Karin sits at the stable Lagrange point in Earth's orbit. A) in circular orbits at the same orbital distance as Jupiter D) Karin is the largest asteroid in a cluster of asteroids that B) in circular orbits at the same orbital distance as Earth all orbit the Sun together. C) in the asteroid belt, so-named because they are large D) in elliptical orbits that cross the orbit of Earth

58. Often, an asteroid viewed from Earth appears to change its brightness periodically because the 65. What kind of orbit is traced by the Trojan asteroids as A) albedo is significantly different on one side than the they move around the Sun? other. A) elliptical orbits that carry them from outside Neptune's B) leading side is very dark and the trailing side is very orbit to inside the orbit of Jupiter bright like , a satellite of Saturn. B) long, elliptical orbits that cross the orbit of Earth C) asteroid is elongated, so it may present a larger or a C) circular orbits at Jupiter's orbital distance, at angles of smaller cross section to us as it rotates. ±60° away from the planet D) asteroid is simply passing through the shadow of another D) circular orbits at about 2.8 AU from the Sun, within the asteroid. asteroid belt

59. In the orbits of which of the planets do Lagrange points 66. What is the orbital sidereal period of a Trojan asteroid? occur? (See Figure 9-13 and Appendix, Table E-1, Comins A) all planets and Kaufmann, Discovering the Universe, 9th Ed.) A) It is difficult to be specific because all Trojan asteroids subjected to other, stronger, gravitational have different orbital periods, depending on influences. As a test of this stability, calculate how their masses. strong Jupiter's gravity is at one of Earth's Lagrange B) 5.9 years, the same as most asteroids in the asteroid belt points (when Jupiter is closest to that point) C) 11.86 years compared with the strength of Earth's gravity at the D) 1.88 years same point. (You will need to use Newton's law of gravitation [see Toolbox 2-3]; it will also help to draw a diagram.) Compared with Earth's 67. If an asteroid were found to be orbiting in a circular path gravitational force at this point, Jupiter's gravity is around the Sun at the same distance as Jupiter (5.2 A) 12 times stronger. AU), what would be its orbital period compared B) 76 times stronger. with that of Jupiter, which is 11.86 years? C) 18 times stronger. A) about 10 times as long as Jupiter's period, or 118.6 years, D) 1/18 as strong. because the Sun's gravitational force is much smaller on such a small object B) about 1/10 of Jupiter's period because it is a much smaller 72. Asteroids whose orbits carry them across Earth's orbit are object known as C) same as Jupiter's period, 11.86 years A) Kirkwood asteroids. D) exactly of Jupiter's period, or 5.93 years, because it B) Amor asteroids. C) Trojan asteroids. would be in a synchronous orbit with Jupiter D) Apollo asteroids.

68. The two Lagrange points in the Jupiter-Sun planetary 73. Asteroids whose elliptical orbits have perihelia inside the system are orbit of Mars but outside the orbit of Earth are A) positions in space at Jupiter's orbital distance from the called _____ asteroids. Sun where the combined gravitational forces A) Apollo from the Sun and Jupiter produce an B) Trojan equilibrium point at which asteroids can C) Hirayama family become trapped. D) Amor B) points at high latitudes on Jupiter where auroras (called

Lagrange auroras on Jupiter) occur most

frequently. 74. What is the difference between an Apollo asteroid and an C) areas in the asteroid belt where gravitational interaction of ? Jupiter with asteroids disturbs their orbits and A) Apollo asteroids cross the orbit of Earth, whereas Amor causes a . asteroids cross the orbit of Mars but not D) an area between the Sun and Jupiter where the Earth's orbit. gravitational forces on an object from these B) Apollo asteroids orbit entirely inside Earth's orbit and massive bodies are equal and opposite. therefore do not cross it, whereas Amor

asteroids cross Earth's orbit and therefore

might hit Earth. 69. The stable Lagrange points associated with two objects in C) Apollo asteroids pass near terrestrial planets, whereas space are points where the combined gravitational Amor asteroids remain in the same orbit as force is Jupiter. A) a minimum. D) Apollo asteroids approach the orbit of Mercury, whereas B) either a maximum or minimum. Amor asteroids pass only within the orbit of C) a maximum. Earth. D) zero.

75. A useful technique for estimating the shapes of many 70. One significant feature of the Lagrange points produced asteroids has been by the Sun and Jupiter is that A) measurement by many closely spaced observers of A) they are regions of reduced gravitational force in the of stars by asteroids. asteroid belt from which asteroids can B) direct photography of the asteroid's shape from Earth. escape, producing the gaps within the belt. C) photography from spacecraft, such as Galileo. B) gravitational forces combine to produce a minimum in the D) measurement of brightness variations caused by asteroid field, thereby trapping asteroids at these rotation. points.

C) gravitational forces combine to enhance the overall force

on particles passing through them, 76. What is unusual about the asteroid Mathilde, which was accelerating them out of the solar system. studied and photographed by the NEAR spacecraft D) they are points of maximum gravitational force near (Figure 9-15a, Comins and Kaufmann, Discovering Jupiter, where the major moons and the Universe, 9th ed.)? are held. A) Mathilde is not much denser than water.

B) Almost no craters are visible anywhere on Mathilde's

surface. 71. Asteroids should be able to remain stably trapped at the C) Mathilde's surface is very bright, possibly a result of fresh Lagrange points of the Earth-Sun system (Figure 9- material thrown out by impacts. 13, Comins and Kaufmann, Discovering the D) Mathilde has a much higher mass for its volume than any Universe, 9th ed.), provided that they are not other known asteroid. with the circular orbits of asteroids in the ecliptic plane. 77. The surfaces of Ida, Mathilde, and , asteroids photographed by the Galileo and NEAR Shoemaker spacecraft (Figures 9-12, 9-15a, and 9-16, Comins 83. The most likely origin of the “dirty snowballs” that and Kaufmann, Discovering the Universe, 9th ed.) become comets when they are deflected into orbits are that bring them closer to the Sun is the A) densely covered with ancient large and small overlapping A) icy surfaces of the and Saturn. craters, similar to the surface of the highland B) dust and gas clouds in the Galaxy. areas of the Moon. C) asteroid belt because most asteroids are actually comet B) irregular, somewhat rounded, and moderately cratered. nuclei. C) covered with ice that is criss-crossed with cracks and D) Kuiper belt and surrounding the solar system. systems of parallel grooves. D) covered with young, sharp, jagged protrusions, due to fragmentation by collision with other 84. To what does the term refer? asteroids, and few craters. A) satellite, or moon, of Pluto B) icy object orbiting the Sun in the region of Pluto C) object in the Oort cloud similar in size to Pluto but 78. Which two spacecraft have taken detailed photographs of orbiting much farther from the Sun the surface of an asteroid? D) object in the Kuiper belt of comet nuclei beyond the orbit A) NEAR Shoemaker and Cassini of Pluto B) Galileo and NEAR Shoemaker C) Magellan and Cassini D) Voyager 1 and Galileo 85. The Kuiper belt is A) another name for the asteroid belt. B) a flat or donut-shaped distribution of distant comets 79. Which spacecraft is the only one known to have landed around the Sun, extending out about 500 AU. on the surface of an asteroid? C) a spherical distribution of distant comets around the Sun, A) Cassini extending out about 50,000 AU. B) Viking D) a random distribution of short-period comets extending C) NEAR Shoemaker from inside the orbit of Jupiter to D) The Soviet Venera 8 spacecraft approximately the orbit of Neptune.

80. What is the purpose of the ? 86. The Oort cloud is A) to plunge into the nucleus of a comet, throwing dust and A) a random distribution of short-period comets extending icy grains out from under the comet's surface from inside the orbit of Jupiter to into space, where they can be seen and approximately the orbit of Neptune. analyzed from Earth B) another name for the asteroid belt. B) to analyze dust samples from other stars and transmit the C) a flat or donut-shaped distribution of distant comets results back to Earth around the Sun, extending out about 500 AU. C) to fly through the tail of a comet and transmit images D) a spherical distribution of distant comets around the Sun, back to Earth extending out about 50,000 AU. D) to collect samples of comet material and bring them back to Earth 87. What is the approximate orbital period of a that orbits the Sun on the outer fringes of 81. The Stardust probe visited Comet Wild 2 and found all the Oort cloud? but one of the following. What did it not find? A) 10 million years A) craters B) 10,000 years B) gas jets C) 100,000 years C) possible fossilized forms like those found in the Mars D) 1000 years D) amino acids 88. What is considered to be the most likely origin of the comets in the Oort cloud? 82. The major difference between the orbital paths of comets A) The comets in the Oort cloud formed in the Oort cloud that we see in the inner solar system and those of more or less where we see them today. the asteroids in the asteroid belt is that B) The comets in the Oort cloud formed in interstellar clouds A) comet orbits are mostly circular and in the ecliptic plane, and were captured by the Sun. whereas the asteroids have elliptical orbits C) The comets in the Oort cloud formed near the orbits of inclined at random to the ecliptic plane. Uranus and Neptune and were flung outward B) asteroids orbit the Sun continuously, whereas all comets by the gravitational influence of these two approach the Sun's vicinity only once before planets. leaving the solar system. D) The comets in the Oort cloud formed near the orbit of C) comets never approach nearer the Sun than approximately Jupiter and were flung outward by Jupiter's Jupiter's orbit, whereas some asteroids immense gravitational pull. approach very near to the Sun. D) cometary orbits are highly elliptical and at random inclinations to the ecliptic plane compared 89. The Oort cloud of comets surrounding the solar system at a distance of about 50,000 AU is believed to be A) material flung outward by the gravity of the newly 96. How large does the , or gas cloud surrounding a formed giant planets early in the history of comet nucleus, become when it reaches its closest the solar system. point to the Sun? B) an through which the Sun and planets A) only 10 km, but it glows brightly in sunlight happen to be passing but is not otherwise B) about 106 km, as big as the Sun connected to the solar system. C) about 108 km, close to the size of Mercury's orbit C) debris left behind at that distance by the collapse of the D) about 107 km, close to 1/10 of Mercury's orbit interstellar cloud that formed the Sun and planets. D) material captured from interstellar space by the Sun's 97. The huge hydrogen cloud that surrounds the nucleus of a gravity. comet, discovered by its UV emission, has a typical diameter of about A) 1/2 AU. 90. Most comet nuclei are believed to be B) 2 ∞ 107 km. A) carbonaceous chondrite meteorites—carbon material— C) 2 AU. ignited by sunlight and resulting in long D) 106 km. smoke trails. B) pieces of dusty ice left over from the formation of the solar system. 98. In a single photograph of a comet and its tail, the only C) pieces of dirty ice ejected from the surface of the icy direction that one can determine with certainty is satellites of the outer planets by asteroid the direction impacts. A) in which the comet is moving, from the trailing tail. D) pieces of rock or iron chipped from asteroids by impacts. B) toward Jupiter because the gravity of this pulls the tail material toward it. C) toward the Sun, indicated by the tail direction because gas 91. The nucleus of Comet Halley, as seen on close-up and dust in the tail are attracted toward the photographs taken by the spacecraft, is Sun by its gravity. A) roughly spherical, moderately cratered, and covered with D) away from the Sun because the tail is pushed in this dark dust. direction by the . B) roughly spherical, light-colored, icy, and covered with many cracks and grooves. C) potato-shaped and darker than coal. 99. Comet tails are the result of D) oblong, with a bright ice surface. A) melting and evaporation of ices from the comet core. B) sunlight glinting on the central icy comet core. C) interplanetary dust collected by the comet as it moves in 92. The measured diameter of the core of Comet Halley is its orbit. about D) interplanetary material streaming into the comet because A) 10 km. of its gravity. B) 106 km. C) 107 km. D) 100 m. 100. The tail of a comet A) is longest when the comet is closest to Jupiter; the tail is pulled out by Jupiter's gravity. 93. Compared with the coma, or the visible fuzzy ball, of a B) remains constant in length throughout its complete orbital comet 106 km in diameter, the diameter of the path. nucleus of the comet is C) is longest when the comet is closest to the Sun. A) about 1/100, or 10,000 km. D) is longest when the comet is farthest from the Sun B) about the size of the largest asteroid, 1/1000, or 1000 km. because it is then unaffected by sunlight. C) extremely small, 1/108, or 10 m. D) very small, about 1/105, or 10 km. 101. A comet's tail always A) points toward the nearest planet, attracted by the planet's 94. The nucleus of a typical comet is gravity field as the comet passes by the A) irregular in shape, with a bright and very reflective, icy planet. surface. B) trails behind the comet in its orbit and so points away B) spherical, with a very smooth, dark surface. from the Sun only while the comet is C) irregular in shape, with a very dark and cratered surface. approaching the Sun. D) spherical, smooth, and very light-colored, being C) points away from the Sun, regardless of the motion of the composed mostly of ice. comet. D) points toward the Sun because the tail is caused by jets of gases evaporated from the comet's nucleus on 95. The size of the coma or gas cloud surrounding the comet the side heated by the Sun. nucleus as it reaches its closest point to the Sun can be as large as A) about 105 km. 102. The gas and ion tail of a comet B) about 10 km. A) is always blown away from the comet in the anti-Sun C) about 107 km. direction by the solar wind. D) about 106 km. B) always lies in the ecliptic plane because a comet is a part of the solar system. C) lies between the comet and the Sun because of A) all located far beyond the orbit of Pluto. gravitational attraction. B) mostly confined to the region between Mars and Jupiter, D) always trails along the orbital path, being left behind by although some comets have orbits that reach the comet. beyond the orbit of Pluto. C) always closer to the Sun than the orbit of Pluto. D) located anywhere from inside the orbit of Pluto to as far 103. The ionized gas tail of a comet is always aligned along as 100,000 AU from the Sun. the A) comet-Sun line. B) line between the comet and the nearest planet to it in its 110. The orbits of periodic comets orbital motion. A) are confined to distances closer to the Sun than the orbit C) comet's direction of motion. of Pluto and are mostly in the ecliptic plane. D) celestial equator. B) can extend far beyond the orbit of Pluto and are primarily in the ecliptic plane. C) are confined to distances closer to the Sun than the orbit 104. A comet's tail always points from the comet head of Pluto and are oriented randomly in the A) toward the nearest planet because of gravitational solar system. attraction for the tail material. D) can extend far out beyond the orbit of Pluto and can be B) toward the Sun because of gravitational attraction. oriented in any direction in the solar system. C) away from the Sun. D) in a direction along its orbital path, always behind the comet. 111. The orbits of comets are A) primarily in the plane of the ecliptic and can extend far out beyond the orbit of Pluto. 105. The particular feature of a comet that exhibits the most B) randomly oriented in the solar system and confined to structure and always points away from the Sun is its distances closer to the Sun than A) hydrogen envelope. approximately the orbit of Pluto. B) ion or gas tail. C) primarily in the plane of the ecliptic and confined to C) coma, or gas cloud. distances closer to the Sun than D) dust tail. approximately the orbit of Pluto. D) randomly oriented in the solar system and can extend far beyond the orbit of Pluto. 106. What mechanism controls the direction in which a comet's ion tail is aligned in space? A) gravitational attraction of the tail material toward the 112. How far will Comet Halley be from the Sun when it giant planet Jupiter reaches its farthest point from the Sun, or aphelion, B) flow of solar wind past the comet's head if its sidereal period is 76 years? (Caution: This C) tail's direction of motion because the tail simply trails calculation needs Kepler's law and a little care. behind the comet in its orbit Assume that the comet's perihelion distance from D) gravitational attraction of the tail material toward the Sun the Sun is negligible.) A) about 18 AU, between the orbits of Saturn and Uranus B) about 1324 AU, well beyond the orbit of Pluto 107. The dust tail of a comet has which group of C) about 9 AU, between the orbits of Jupiter and Saturn characteristics? D) about 36 AU, between the orbits of Neptune and Pluto A) spherical, very large, and of low brightness, centered on the comet nucleus, showing up only on UV photographs 113. What is Sedna? B) curved, wide, and without structure, but thin and A) largest object discovered beyond the orbit of Pluto transparent to starlight B) bright comet to which we hope to send a rendezvous C) long, straight, structured, and pointed directly away from mission the Sun C) largest object in the asteroid belt D) narrow and straight and pointed directly at the Sun at all D) largest of the Trojan asteroids times

114. What causes the dust tail of a comet to separate from 108. Dust grains released by the melting of ice in a comet the nucleus? nucleus A) radiation pressure A) drift away from the Sun along magnetic field lines, B) gravity outlining the structure of the field. C) magnetic repulsion B) become a straight, highly structured, and very variable tail D) collisions with the solar wind blown away from the comet by the solar wind. C) become a cloud around the nucleus, the coma, scattering 115. How does the dust tail of a comet compare with its gas sunlight very efficiently at blue wavelengths. tail? D) become a uniform, curved tail moving away from the A) Dust tails often appear blue and gas tails white. comet under radiation pressure from sunlight. B) Dust tails are straight, whereas gas tails are curved. C) Dust tails are more massive than gas tails. D) Dust tails point toward the sun, whereas gas tails point 109. The aphelia (farthest distances from the Sun) of the away. orbits of periodic comets are 122. The longest period for a comet that can be considered a 116. What is the purpose of the Genesis spacecraft? Jupiter family comet is 20 years. If the perihelion of A) to land on an asteroid such a comet's orbit is very close to the Sun, where B) to move alongside a bright comet nucleus is aphelion? C) to collect some of the solar wind and return to Earth A) between the orbits of Jupiter and Saturn D) to collect several small asteroids and return to Earth B) between the orbits of Saturn and Uranus C) between the orbits of Uranus and Neptune D) in the Kuiper Belt 117. The mission sent an impactor crashing into Comet . What happened? A) The impactor disappeared into the rubble and regolith 123. A typical comet in an elliptical orbit around the Sun will covering the comet's nucleus without leaving lose what fraction of its mass by melting each time a trace. it passes close to the Sun (i.e., at each perihelion B) The impactor incinerated in the comet's coma and never passage)? reached the nucleus. A) 1/1000 C) The comet was shattered into many small fragments. B) very small fraction, less than 1/10,000 D) The collision caused a huge cloud of debris, but 90% of it C) 1/10 was pulled back to the surface by the nucleus' D) 1/100 gravity.

124. The number of times a typical comet can pass close to 118. What did we learn from the Deep Impact mission to the Sun (i.e., the number of orbits the comet can Comet Tempel 1 in 2005? complete) before it is completely vaporized or A) A comet of this size can be completely shattered by a destroyed is about rather minor impact. A) 1 million. B) Comet nuclei are highly radioactive. B) 1000. C) The dust thrown up by the impact showed evidence of C) 1. organic molecules. D) 100. D) The mission success or failure to collect samples will not be known until the spacecraft returns to Earth. 125. Suppose a comet is observed to have a surface of pure ice with very little dust and rock on its surface. What can we say about this comet? 119. The images of the Deep Impact encounter with Comet A) The comet originated in the Kuiper belt rather than the Tempel 1 in 2005 (see Figure 9-30, Comins and Oort cloud. Kaufmann, Discovering the Universe, 8th ed.) show B) The comet is probably making its first passage near the the nucleus looking like a solid piece of rock and Sun. not like a fiery comet with a glowing tail. Why is C) The comet is very old, having made many trips around the the glowing gas we usually associate with a comet Sun. absent? D) The comet is part of the family of Kreutz comets. A) This is an unsolved mystery and one of the reasons this comet was chosen for investigation. B) Comet Tempel 1 is a very old comet, and almost all of the 126. A shooting star is a volatile material is gone. A) violently erupting star ejecting matter rapidly away from C) A comet evolves glowing gases only when it is near the it into interstellar space. Sun, and Comet Tempel 1 never gets close B) near-neighbor star moving rapidly across our field of enough to the Sun to evolve a tail. view. D) Comet Tempel 1 is, in fact, a solid rock and shows no C) leading scorer on a basketball team. evidence of ice. D) small particle of interplanetary dust burning up and glowing as it enters Earth's atmosphere.

120. The collision of the Deep Impact probe with the nucleus of Comet Tempel 1 in 2005 revealed the nucleus as 127. When a piece of enters Earth's atmosphere a “,” held together by it makes a bright streak. There are several names A) cohesive forces much stronger than those holding rocks for this flash of light, Which of the following is not together on Earth. one of these? B) frozen ices. A) shooting star C) gravitation. B) fireball D) a fusion crust. C) bolide D) meteroid

121. What defines a comet as a long-period comet? A) The comet makes only one pass near the Sun and then 128. The luminous trails of small dust particles that are leaves the solar system forever. completely vaporized in Earth's atmosphere are B) The comet falls in from the Oort cloud rather than from known as the Kuiper belt. A) auroral flashes. C) The comet has a period longer than 1000 years. B) meteorites. D) The comet has a period longer than 200 years. C) meteors. D) .

136. Most meteor showers occur when Earth moves through 129. A chunk of rock and metal 10 km in diameter orbiting the the Sun would be called a(n) A) orbit of a comet (or of a former comet). A) asteroid. B) Kuiper belt. B) comet. C) asteroid belt. C) moon. D) Oort comet cloud. D) meteoroid.

137. A occurs when 130. A small particle of rock orbiting the Sun would be A) the head of a comet hits Earth's atmosphere. called a B) a meteor disintegrates in Earth's atmosphere. A) meteor. C) Earth passes through the asteroid belt. B) micrometer. D) Earth passes through a swarm of dust particles in space. C) meteorite. D) meteoroid. 138. A meteor shower results from A) material ejected by a massive impact on the Moon; 131. Meteoroid is the term used to describe a solid particle Earth's gravity attracts it toward Earth. that B) material reentering Earth's atmosphere after being ejected A) is drifting around in space. into space by violent volcanic eruptions on B) has fallen to Earth from space. Earth. C) burns up as it falls through Earth's atmosphere. C) Earth passing through debris of an old comet. D) originated on the Moon but was knocked onto Earth by a D) a small piece of rock fragmenting as it passes through massive impact. Earth's atmosphere.

132. The Barringer meteorite crater is located in 139. A meteor shower, or the appearance of many more A) Australia. “shooting stars” at a particular time in the year from B) the Yucatán Peninsula, Mexico. a specific sky direction, is related to which C) Quebec, Canada. astronomical phenomenon? D) Arizona, U.S.A. A) passage of Earth through the remnants of an old comet B) passage of Earth through intense streams of solar wind C) Earth's passage through part of the asteroid belt 133. The estimated impact energy of the object that produced D) Earth's passage through different parts of the spiral arms the Barringer Crater in Arizona, in terms of of the Galaxy explosive power (tons of TNT equivalent, a somewhat dubious and frightening scale!), is A) greater than 1000 megatons. 140. Why do the meteors that are seen in the sky in a B) about 1 megaton. particular meteor shower appear to come from one C) about 20 megatons, similar to the most powerful specific direction in the sky? hydrogen bombs. A) The meteors only appear to come from a specific D) similar to the first nuclear weapons—less than 10 direction because of Earth's orbital motion. kilotons. B) The meteors appear this way because the direction is that of the orbit of the comet that disintegrated to produce the shower. 134. The cause of the “meteor showers” seen at regular times C) This direction is always along the ecliptic plane because each year on Earth is most probably meteor showers occur when Earth catches up A) Earth running into material within the spiral arm structure with a collection of particles moving in its of the Milky Way. orbit. B) unstable weather conditions on Earth. D) This direction is the one along which objects pass on C) Earth moving through the remnant dust and rock being attracted to the Sun from fragments of an old comet that are orbiting by the Sun's gravity. the Sun in the comet's old orbit. D) sunspot activity and the resultant geomagnetic disturbances. 141. A piece of rock from outer space that reaches Earth's surface after surviving a fiery passage through Earth's atmosphere is known as a(n) 135. What causes a meteor shower? A) meteoroid. A) If Earth happens to be near a comet when it breaks up, we B) asteroid. will see a shower as debris enters Earth's C) meteor. atmosphere. D) meteorite. B) Earth passes through the orbit of a comet. If the comet happens to be nearby, the normal ejecta from the nucleus will cause a shower. 142. In order of abundance, from most abundant to least C) Earth passes through the tail of a comet. abundant, the occurrence of meteorite impacts D) Earth passes through the orbit of a former comet that has (“falls”) is believed to be become strewn with debris. This enters our A) stony, iron, stony iron atmosphere and causes showers. B) stony iron, iron, stony C) iron, stony iron, stony D) stony, stony iron, iron C) 50% D) 95% 143. From which planet is the meteoritic material found recently in Antarctica believed to have come? A) Venus 151. For which of the following descriptions would you B) Mars identify a rock as a fallen meteorite? C) Mercury A) basalt rock full of hollow spaces, shiny and dark colored, D) Jupiter with fine details on its surface B) rock containing large, transparent crystals of common salt embedded in sandstone 144. The estimated total infall of meteoritic and C) layered rock consisting mainly of limestone extraterrestrial material from space per day on D) irregular and very heavy solid iron rock with a distinctive Earth is crystal structure throughout its interior A) about 30 tons. B) less than 1 ton. C) about 1 million tons. 152. The Widmanstätten pattern found in many iron D) about 300 tons. meteorites consists of A) a myriad of small iron crystals formed when the rock cooled quickly in the vacuum of space. 145. Interplanetary material B) small holes created by the heating and partial melting of A) falls on Earth at the rate of several hundred tons per day, the meteorite as it entered Earth's mostly as micrometeoroids. atmosphere. B) occasionally hits Earth in the form of fairly large objects C) fracture lines created by the original impact that knocked that form craters, but there is no continuous the meteoroid off the parent asteroid. stream of incoming matter. D) large crystals formed as the iron cooled slowly over many C) hits Earth at specific times of the year in the form of small millions of years. particles that produce meteor showers, but interplanetary material does not fall on Earth at other times. 153. The Widmanstätten pattern of crystals found in many D) falls on Earth only very rarely in the form of single large iron meteorites is evidence that the meteorites objects, but these individual impacts can A) cooled slowly over many millions of years. devastate parts of Earth and threaten life. B) cooled quickly, in only a few years at most. C) have suffered highly energetic collisions with asteroids or other meteorites. 146. Which are the most common types of meteoroids in D) have been subject to periodic heating by close approaches space? to the Sun. A) stony irons B) stones C) irons 154. Widmanstätten patterns are a test for which kind of D) carbonaceous chondrites meteorite? A) stones B) stony irons 147. The most common meteorites to hit Earth are C) irons A) carbonaceous chondrites. D) carbonaceous chondrites B) iron meteorites. C) stony iron meteorites. D) stony meteorites. 155. Most meteorites show evidence of having melted or of being fragments of asteroids that were once differentiated by heat. Carbonaceous chondrites, 148. Stony meteorites however, are believed to have never melted. Which A) are very much like ordinary silicate rocks. one of the following sentences is NOT a reason we B) contain large quantities of carbon and water and even believe carbonaceous chondrites have never hydrocarbons and amino acids. melted? C) have solid iron cores surrounded by rocky silicate shells. A) Carbonaceous chondrites contain complex carbon D) are made of solid iron and small quantities of nickel and compounds that would have been broken cobalt. down into simpler compounds by high heat. B) The minerals in carbonaceous chondrites contain as much as 20% water. The water would have been 149. What fraction of the material arriving on Earth from driven out if the minerals had been heated. outer space is in the form of iron meteorites? C) Amino acids that are occasionally found in carbonaceous A) 50% chondrites would have been destroyed by B) a few % melting. C) 95% D) Carbonaceous chondrites do not show fusion crusts after D) 10 to 20% passage through Earth's atmosphere.

150. What fraction of the material arriving on Earth from 156. Carbonaceous chondrite meteorites have been found to outer space is in the form of stony meteorites? contain all of the following except one. Which has A) a few % not been found? B) 10 to 20% A) small glass-rich beads called chondrules B) minerals that contain water A) Carbonaceous chondrites show a Widmanstätten pattern, C) amino acids which indicates slow condensation from D) interior rock that has obviously been melted and re- gaseous material. solidified. B) The minerals of a carbonaceous chondrite contain up to 20% water, which would have evaporated away if the chondrite had been strongly 157. Stony iron meteorites are believed to heated. A) have been ejected by volcanoes on Mars. C) Carbonaceous chondrites consist mostly of carbon, which B) originate from differentiated asteroids (in which iron sank was the dominant substance condensing in to the center). the outer solar nebula. C) be pieces of primordial solar system material, unaltered D) Carbonaceous chondrites consist almost entirely of ice, since the solar system formed. which would have sublimed away by now if D) originate from undifferentiated asteroids (same this were not the first time the chondrite was composition throughout). passing close to the Sun.

158. The existence of distinct and separate types of 163. Perhaps the most interesting and puzzling material to be meteorites, stony, stony iron, and iron, is probably a found inside rocks that have come from outer space result of is A) differentiation of material in molten asteroid interiors, A) water. with the iron sinking to the core, followed by B) radioactive material. fragmentation and separation of the iron core C) pure iron. and rocky shell. D) amino acids, or proteins. B) preferential of iron particles to other iron particles because of their magnetic properties, leaving stony particles to accrete 164. A stony meteorite would not show evidence of which separately. one of the following properties? C) different amounts of heating and “erosion” of the outer A) carbonaceous chondrites layers of meteorites as they pass through B) fusion crust Earth's atmosphere; the irons lose their outer C) former deposits of a short-lived radioactive isotope of rocky shells. aluminum D) their formation in different parts of the early solar nebula, D) Widmanstätten pattern with stones condensing closer to the Sun and irons condensing farther away from the Sun. 165. The 1908 Tunguska Event resulted in three of the following. Which one was not a result? 159. Which meteorites are believed to be samples of A) a huge dust cloud primordial solar nebula material? B) a loud explosion A) carbonaceous chondrites C) a huge shock wave B) stony irons D) a large crater C) meteorites showing Widmanstätten patterns when etched with acid D) irons 166. Recent calculations show that the Tunguska explosion in Siberia in 1908 was probably caused by a A) large stony meteorite about 1 m across striking the ground 160. Which of the following biochemical materials have at a high speed. been found and identified in carbonaceous B) small nuclear explosion. chondrites that have hit Earth? C) small comet nucleus about 1 km across suddenly A) living viruses vaporizing in the atmosphere. B) amino acids, or proteins D) small stony asteroid about 80 m across exploding well C) lichens and mosses above the ground. D) living single-cell organisms

167. What has been discovered in some meteorites that 161. Which of the following characteristics of carbonaceous suggests that the formation of our Sun and solar chondrites is unusual compared with other system might have been triggered by a supernova meteorites? explosion? A) Carbonaceous chondrites never show Widmanstätten A) decay products of short-lived radioactive elements, which patterns. only could have been produced in intense B) Carbonaceous chondrites contain water—a sure sign that nuclear reactions they have never melted. B) super-pure iron, produced only in nuclear reactions C) Carbonaceous chondrites show a fusion crust—a sure sign C) fusion crusts around most meteorites, indicating that they of short-lived, rapid heating. were heated intensely at some time in their D) Carbonaceous chondrites contain rocky material—a sure history sign that they come from a differentiated D) amino acids, which can be produced only in very specific asteroid. conditions

162. Why are carbonaceous chondrites thought to be original 168. A meteorite that recently fell to Earth was found to material that formed in the early solar nebula? contain evidence of the existence earlier in its history of a short-lived radioactive isotope of B) create significant damage near the impact site but have aluminum, 26Al, which can be produced only under relatively little lasting worldwide effect. extremely energetic conditions and in nuclear C) shatter Earth into fragments. reactions. What conclusion can be drawn from this D) completely destroy life on Earth. observation? A) An energetic nuclear event, a supernova, occurred near the Sun, and it produced the 26Al at about the 173. An impact that took place at about the time of the time the meteorite was formed. extinction of the dinosaurs (and may in fact have B) The meteorite became so hot on its descent through caused their extinction) is believed to have created Earth's atmosphere that it became A) Barringer Crater in Arizona. radioactive, and the 26Al was formed at that B) Manicouagan Crater in Quebec. time. C) Hudson Bay in northern Canada. C) The meteorite had probably passed through radioactive D) Chicxulub Crater in the Yucatán Peninsula. clouds in space and collected the 26Al before hitting Earth. D) Radioactivity occurs spontaneously in normal matter, so 174. The Chicxulub Crater, believed by many scientists to this finding is not surprising. have been created by the impact that caused the extinction of the dinosaurs, is A) an eroded, water-filled depression in the Canadian Shield 169. The Allende meteorite contained an abundance of 26Mg, area of northern Quebec. an isotope of magnesium. What is the significance? B) hidden under the Yucatán Peninsula and adjacent A) Magnesium has a high melting point, so the asteroid of Carribean Sea. which Allende was originally a part must C) a prominent landmark in northern Arizona. have formed in the inner part of the solar D) a large, round valley with a central peak high in the system. Andes Mountains. B) 26Mg is radioactive, and the sample was probably produced in a nearby supernova explosion about the time the solar system was formed. 175. What is the specific mechanism by which the Chicxulub C) 26Mg is the stable product of the decay of radioactive 26Al. impact is believed to have caused the extinction of The 26Al from which the 26Mg formed was the dinosaurs and many other species 65 million probably produced in a nearby supernova years ago? explosion about the time the solar system was A) Iridium poisoning due to fallout of meteoritic material formed. destroyed a large fraction of the creatures D) This discovery suggests that heavy elements such as within several days of the impact. magnesium were more abundant in the early B) Dust thrown up by the impact blotted out the Sun and Kuiper belt than we had originally thought. disrupted the food chain over a period of several years. C) The incoming asteroid contained alien biological material 170. The metal that is relatively abundant in meteorites but is that destroyed susceptible species within a generally rare on Earth has been found in specific few weeks of the impact. layers of clay throughout the world, and its study is D) Shock waves and tsunamis (tidal waves) killed the helping to evaluate the effect of meteor impacts on majority of living creatures within a few Earth's climate and its inhabitants in recent minutes of the impact. geological time (e.g., dinosaurs). This metal is A) iron. B) nickel. 176. What is the likely connection between the metal iridium C) cobalt. and the demise of Earth's dinosaur population? D) iridium. A) Iridium, which is found in abundance on Earth's surface, is poisonous to reptiles. B) Iridium is found beneath Earth's crust. Meteor impacts 171. The astronomical event that is now thought to have during the dinosaur age probably exposed occurred some 65 million years ago, resulting in the and uncovered enough of it to poison the of a large fraction of all living species and dinosaurs. leaving a layer of clay containing an enhanced C) Iridium is found in meteorites but is rare on Earth. The concentration of a rare metal, iridium, in the existence of a worldwide layer of it suggests geological record in rocks throughout Earth was a large meteor impact during the dinosaur a(n) age. The impact probably raised enough dust A) extraordinary solar eruption or flare. to block out sunlight and kill the dinosaurs. B) very large volcanic eruption on Earth. D) Iridium is highly radioactive. Its presence in a geologic C) supernova that exploded relatively close to the solar layer dating to the dinosaur age suggests that system. natural radioactivity reached dangerous D) asteroid impact on Earth. levels at that time, and the dinosaurs died from overexposure.

172. On the basis of the recent interpretation of geological evidence, the impact of a 10-km-diameter asteroid 177. Rocks laid down at around the time of the on the surface of Earth would be very likely to Permian/Triassic mass extinction 250 million years A) disrupt the global ecology and cause the extinction of a ago contain a surprising amount of fullerenes large percentage of all species living on (football-shaped carbon molecules). What evidence Earth. is there that the fullerenes came from outer space? A) The isotope ratio of carbon13 to carbon12 is too great for 179. The ecliptic is the plane defining Earth's orbit around the fullerenes to have originated on Earth. the Sun. The orbits of most other objects in the B) The fullerenes show evidence of having been irradiated solar system generally lie fairly close to the ecliptic. by the solar wind for millions of years. However, the orbits of which one of the following C) Gases trapped inside the fullerenes could have come only types of objects do NOT generally lie close to the from stars. ecliptic? D) The rocks in which the fullerenes are found contain decay A) Trojan asteroids products of short-lived radioactive aluminum B) asteroid belt asteroids isotopes that are believed to be produced only C) comets in supernovae (explosions of stars). D) Kuiper belt objects

178. At the end of the Permian era 250 million years ago, 180. Fullerenes (“buckeyballs”) are spherical molecules 70% of all species living on land and 90% of all composed exclusively of carbon atoms. What is species living in the oceans disappeared. What is their connection with meteoric impacts? believed to have been the cause of this massive A) Fullerenes are not produced naturally on Earth, so any extinction? fullerenes found here must have been carried A) global warming from volcanic gases released during the here from space. breakup of the Gondwanaland supercontinent B) Fullerenes are not produced naturally on Earth, but they B) nearby supernova (the explosion and total destruction of a can be created in the tremendous heat and star) compression of a large meteoric impact. C) devastating impact by an asteroid C) Fullerenes with gas molecules trapped inside could only D) “snowball Earth” episode in which global cooling caused have been produced in supernova explosions. Earth's ocean surfaces to freeze and glaciers D) Fullerenes with gas molecules trapped inside could only to cover the continents have been produced in the tremendous heat and compression of a large meteoric impact.

Answer Key - Chapter 9: Vagabonds of the Solar System

1. D 41. A 81. C 121. D 161. B 2. D 42. A 82. D 122. B 162. B 3. A 43. D 83. D 123. D 163. D 4. A 44. B 84. B 124. D 164. D 5. D 45. B 85. B 125. B 165. D 6. D 46. A 86. D 126. D 166. D 7. A 47. C 87. A 127. D 167. A 8. D 48. C 88. C 128. C 168. A 9. D 49. B 89. A 129. A 169. C 10. D 50. D 90. B 130. D 170. D 11. C 51. C 91. C 131. A 171. D 12. D 52. C 92. A 132. D 172. A 13. B 53. D 93. D 133. C 173. D 14. D 54. D 94. C 134. C 174. B 15. D 55. D 95. D 135. D 175. B 16. A 56. A 96. B 136. A 176. C 17. D 57. D 97. B 137. D 177. C 18. B 58. C 98. D 138. C 178. C 19. C 59. A 99. A 139. A 179. C 20. A 60. D 100. C 140. B 180. C 21. D 61. D 101. C 141. D 22. C 62. C 102. A 142. A 23. C 63. D 103. A 143. B 24. C 64. A 104. C 144. D 25. B 65. C 105. B 145. A 26. D 66. C 106. B 146. B 27. A 67. C 107. B 147. D 28. D 68. A 108. D 148. A 29. D 69. A 109. D 149. B 30. B 70. B 110. D 150. D 31. D 71. C 111. D 151. D 32. D 72. D 112. D 152. D 33. A 73. D 113. A 153. A 34. D 74. A 114. A 154. C 35. C 75. D 115. C 155. D 36. D 76. A 116. C 156. D 37. C 77. B 117. D 157. B 38. A 78. B 118. C 158. A 39. C 79. C 119. C 159. A 40. C 80. D 120. C 160. B