Practice Final - OL Class - Answers PDF

Practice Final Name:____________________ Multiple Choice 1. You discover a round object orbiting Saturn. How would you classify this object? a. as a planet d. as a Kuiper Belt Object b. as a dwarf planet e. as a moon c. as an asteroid 2. You discover a pota...

Practice Final Name:____________________ Multiple Choice 1. You discover a round object orbiting Saturn. How would you classify this object? a. as a planet d. as a Kuiper Belt Object b. as a dwarf planet e. as a moon c. as an asteroid 2. You discover a potato shaped object orbiting the Sun at a distance of 350 AU. How would you classify this object? a. as a planet d. as a Kuiper Belt Object b. as a dwarf planet e. as a moon c. as an asteroid 3. You discover an object with a diameter of 3500 km orbiting the Sun at a distance of 60 AU. How would you classify this object? a. as a planet d. as a Kuiper Belt Object b. as a dwarf planet e. as a moon c. as an asteroid 4. You discover a round object orbiting the Sun at a distance of 3 AU. How would you classify this object? a. as a planet d. as a Kuiper Belt Object b. as a dwarf planet e. as a moon c. as an asteroid 5. You discover an object with a diameter of 45,000 km orbiting the Sun at a distance of 25 AU. How would you classify this object? a. as a planet d. as a Kuiper Belt Object b. as a dwarf planet e. as a moon c. as an asteroid 6. You discover an object with a diameter of 750 km orbiting the Sun at a distance of 150 AU. How would you classify this object? a. as a planet d. as a Kuiper Belt Object b. as a dwarf planet e. as a moon c. as an asteroid 7. Suppose that you use a basketball to represent the Sun in a scale model of the solar system. Which object could you use to best represent Uranus? a. a baseball d. a bb gun ball b. a ping pong ball e. a sand grain c. a marble 8. Suppose that you use a basketball to represent the Sun in a scale model of the solar system. Approximately how far away should you place the object representing Neptune? a. 3 feet d. 3,300 feet b. 33 feet e. 33,000 feet c. 330 feet 9. How many planet Mars fit across the diameter of Saturn? a. 2 d. 1,700 b. 17 e. 17,000 c. 170 10. Suppose that you use a 5-inch ball to represent the Earth in a scale model of the solar system. Approximately how far away should you place the object representing the Sun? a. 6 inches d. 6,050 inches b. 60 inches e. 60,500 inches c. 605 inches 11. In a model of the solar system, you use a basketball to represent the Sun and a baseball to represent Saturn. You place the two objects 1050 feet apart. Is this an accurate scale model? a. Yes, it is an accurate scale model. b. No, the object representing Saturn needs to be bigger. c. No, the object representing Saturn needs to be smaller. d. No, the baseball and basketball need to be closer together. e. No, the baseball ball and basketball need to be further apart. For questions 12-16, match the mission purpose with the appropriate mission type. The options are: a. flyby d. rover b. orbiter e. impactor c. lander 12. You would like to send a mission to Ganymede to map the topography and composition of the entire surface. Orbiter 13. You would like to send a mission to Titan to see if there are organic molecules buried directly underneath the surface. Impactor 14. You would like to send a mission to Mars to look for evidence of past life in a dried streambed. Rover 15. You would like to send a mission to Saturn to get a broad overview and understanding of the characteristics of several of its moons. Flyby 16. You would like to send a mission to Europa to place a seismometer on the surface to track any earthquakes that occur. Lander Questions 17 to 19 refer to the table below. Mass Planet Semi-Major Axis (AU) Eccentricity (in terms of Earth’s mass) A 2 1.5 0.023 B 1.5 1 0.056 C 1.5 2 0.0098 D 3 2 0.032 17. Which planet has the most circular orbit? a. planet A c. planet C b. planet B d. planet D 18. Rank the planets in terms of orbital period from longest to shortest. a. D>B=C>A d. B>D>A>C b. C=D>A>B e. D>C>B>A c. D>C>A>B 20. Which planet will experience the least change in orbital velocity during one orbit (revolution)? a. planet A c. planet C b. planet B d. planet D 21. If Mercury were moved to the Earth’s orbit, how would its orbital period change? a. The period would be longer. b. The period would be shorter. c. The period would not change. 22. A planet travels the same distance in its orbit from point A to B as from point C to D. Which of the following statements must be true? a. The speed from A to B is the same as the speed from C to D. b. The time from A to B is the same as the time from C to D. c. Both A and B must be true. d. Neither A nor B are necessarily true. 23. The diagram above illustrates Earth’s orbit around the Sun (not to scale). During which month does the Earth travel the fastest? a. April d. January b. July e. the speed remains the same c. November The figure below shows Earth’s orbit around the Sun, with Earth’s location marked for four different points in the orbit. Questions 24-26 refer to this diagram. 24. When the Earth is at position D, what season is New York experiencing? a. winter c. summer b. spring d. fall 25. When the Earth is at position C, what season is Australia experiencing? a. winter c. summer b. spring d. fall 26. At which letter is the Earth furthest from the Sun? a. A c. C b. B d. D 27. Why do we experience seasons? a. The Earth’s orbit is elliptical. When we are closer to the Sun, it is summer. b. The Earth’s axis is tilted. When we are tilted towards the Sun, it is summer because we are closer. c. The Earth’s axis is tilted. When we are tilted towards the Sun, it is summer because we get more concentrated sunlight. d. The Earth rotates. When we are facing the Sun, it is summer. 28. In the winter, we have a. more hours of daylight than in summer. b. less hours of daylight than in summer. c. the same hours of daylight as in summer. 29. If the Earth’s axis of rotation were more tilted, a. winter would be warmer that it is now. b. winter would be colder than it is now. c. winter would be the same temperature as it is now. 30. What is the name of the moon phase shown above? a. first quarter d. waxing gibbous b. third quarter e. waning gibbous c. full The diagram below illustrates the orbit of the moon around the Earth. Questions 31-33 refer to this diagram. 31. Where would the moon be when it is in the phase shown in question 1? a. A d. D b. B e. E c. C 32. What phase is the moon in when it is at position E? a. new d. waning gibbous b. full e. waxing crescent c. waxing gibbous 33. If the moon is currently in position D, how long will it be until it is in the new moon phase? a. half of a week d. 3 weeks b. 1 week e. it is in the third quarter phase now c. 2 weeks 34. If the moon is at position C, what time will it set? a. 3 am d. 9 pm b. 3 pm e. 9 am c. midnight 35. You see a moon rising in the east at noon. What phase are you seeing? a. waxing gibbous d. waning crescent b. waning gibbous e. waxing crescent st c. 1 quarter 36. Which planets formed at locations below the freezing point of water? a. Earth, Mars, Jupiter, Saturn, Uranus, Neptune d. Uranus and Neptune b. Mars, Jupiter, Saturn, Uranus, Neptune e. all of the planets c. Jupiter, Saturn, Uranus, Neptune 37. Would you expect a Jovian planet to have formed in the orbit of Mars? a. Yes, because Jovian planets can form anywhere. b. Yes, because it is currently too cold for liquid water on Mars. c. No, because during formation temperatures were too hot for liquid water. d. No, because there was no hydrogen or helium gas there during formation. e. No, because planets here would have grown too fast to hold onto a lot of gases. 38. You discover a new solar system where the temperature during formation was 400 K at a distance of 8 AU. What type of planet do you expect to find at 5 AU in this solar system? Please note that water freezes at 273 K and boils at 373 K. a. a Terrestrial planet c. it is impossible to say b. a Jovian planet 39. In a solar system around a star that is hotter than our own Sun, where will the Jovian planets be located? a. Closer to their star than our Jovian planets are from the Sun. b. Further from their star than our Jovian planets are from the Sun. c. At the same distance from their star as our Jovian planets are from the Sun. 40. Which observation does NOT tell us something about the way in which our solar system formed? a. the planets mostly spin on their axes in the same direction b. the rocky planets are closer to the Sun, and the gaseous planets are further c. the Jovian planets have rings but the Terrestrial planets do not d. the planets all orbit the Sun in the same direction e. the planets all orbit the Sun in the same plane 41. The diagram above illustrates four different stages in solar system formation. Place the stages in order from first to last. a. B,C,D,A c. D,B,C,A b. C,B,D,A d. A,B,C,D 42. Match the following features with what they tell you about a planet: impact craters, volcanoes, divergent ridges, stream beds, sand dunes. a. This planet has/had an atmosphere. Sand dunes b. This planet has/had liquid water. Stream beds c. This planet has/had a molten interior. Volcanoes d. This planet has/had a molten interior and plate tectonics. Divergent ridges e. This planet has been hit by a rock from space. Impact craters Questions 43-46 refer to the table below. For reference, the Earth has a diameter of 12,742 km. Planet Distance from Star Diameter (km) (AU) Planet A 0.6 AU 2,345 Planet B 1.2 AU 13,462 Planet C 5.3 AU 4,563 Planet D 10.2 AU 14,213 43. The table above shows a made-up solar system with 4 planets. Assuming the solar system is the same age as our own solar system, then which planets would you expect to still be geologically active? a. just D d. none of the planets b. B and D e. all of the planets c. A and C 44. Rank the planets from those which will become geologically dead first to those which will become geologically dead last. a. D > C > B > A d. A > C > B > D b. A > B > C > D e. A = B = C = D c. A > D > C > B 45. Which features would you expect to be currently forming on planet B? a. impact craters d. all of the above b. sands dunes e. none of the above c. volcanoes 46. Which features would you expect to be currently forming on planet A? a. impact craters d. all of the above b. sands dunes e. none of the above c. volcanoes 47. Suppose that you find a geologically active Mercury-sized planet in a different solar system. This solar system is probably a. older than ours c. the same age as ours b. younger than ours 48. Planet A and B are both made of ice and rock. Planet A is bigger, and composed of ½ rock and ½ ice. Planet B is composed of ¼ rock and ¾ ice. Which planet is denser? a. planet A b. planet B c. they have the same density d. it is impossible to say 49. Planet A and B are both made of rock and ice. Planet A is bigger. Which has the higher density? a. planet A b. planet B c. they have the same density d. it is impossible to say 50. A planet has a hot interior and plate tectonics, but no liquid water on the surface. Which rock types would you expect to find forming on this planet? a. just igneous rocks b. both igneous and sedimentary rocks c. both sedimentary and metamorphic rocks d. both igneous and metamorphic rocks e. igneous, sedimentary, and metamorphic rocks 51. Which type of rock forms from cooling liquid rock? a. sedimentary c. metamorphic b. igneous 52. How do we know that the Earth’s outer core is liquid? a. because no earthquake waves can travel through the Earth’s center b. because we have drilled to the center and brought out samples c. because the magma erupted by volcanoes comes from the outer core d. because S-waves can’t travel through the Earth’s center, but P-waves can 53. Planet A and B are the same size. Earthquakes on Planet A produce a smaller S-wave shadow zone than earthquakes on Planet B. Which planet has the larger liquid outer core? a. Planet A b. Planet B c. it is impossible to say 54. Crater B is infilled with lava, and Crater A is not. Crater A lies on top of Crater B. Which crater is older? a. Crater A b. Crater B c. it is impossible to say 55. Neither Crater A nor Crater B are infilled with lava. The craters do not overlap. Which crater is older? a. Crater A b. Crater B c. it is impossible to say The diagram below shows three cratered areas of the moon. Suppose that rocks samples show area B to be 16 million years old, and recall that cratering rate = number of craters/time, and time = number of craters/rate. Questions 56-58 refer to this diagram. 56. What is the cratering rate? a. 64 craters/million years d. 1 crater/million years b. 16 craters/million years e. 0.25 craters/million years c. 4 craters/million years 57. How old is area A? a. 64 million years old d. 1 million years old b. 16 million years old e. 0.25 million years old c. 4 million years old 58. How many more impacts do you expect area B to accumulate in the next 8 million years? a. 0 d. 4 b. 1 e. 16 c. 2 59. In the cratered areas above, which area has been partially resurfaced? a. the left box c. the right box b. the middle box d. it is impossible to say 60. Which of the following IS a likely short-term effect of a giant (Chicxulub-sized) impact? a. destruction of ozone layer d. ice age b. global warming e. earthquakes c. volcanic eruptions 61. Which of the following IS a likely long-term effect of a giant (Chicxulub-sized) impact? a. destruction of ozone layer d. volcanic eruptions b. earthquakes e. ice age c. impact winter 62. Using the plot provided at the end of the exam, how often do events involving a 5,000 meter impactor occur? a. about once every 1,000 years b. about once every 10,000 years c. about once every 100,000 years d. about once every 1 million years e. about once every 10 million years 63. Using the plot provided at the end of the exam, impactors with a diameter of 100 m hit the Earth __________ than impactors with a diameter of 10,000 m. a. less frequently b. about 500 times more frequently c. about 5,000 times more frequently d. about 50,000 times more frequently 64. A certain sized impact has a recurrence interval of 4 years. What is the chance of an impact this size occurring this year? a. 0% d. 25% (1/4) b. 5% (1/20) e. it depends on when the last one happened c. 10% (1/10) 65. A certain sized impact has a recurrence interval of 500 years. How many of these impacts would you expect in a period of 5000 years? a. 0 d. 500 b. 5 e. 1000 c. 10 66. The lunar lowlands formed a. from rock that rose to the surface and cooled in a magma ocean. b. from sedimentary rock deposition in lakes. c. from lava welling up through impact-generated cracks. d. from the convergence of tectonic plates. e. from comets depositing icy layers on the surface. 67. True or False: The lunar highlands and lowlands are composed of different rocks. 68. True or False: The lunar highlands have fewer craters than the lowlands. 69. Considering the following events in lunar history, which happened last: late heavy bombardment, formation of highlands, cooling of interior, formation of lowlands, came together from orbiting debris. a. late heavy bombardment 3 b. formation of highlands 2 c. cooling of interior 5 d. formation of lowlands 4 e. came together from orbiting debris 1 70. Considering the following events in lunar history, which happened third: late heavy bombardment, formation of highlands, cooling of interior, formation of lowlands, came together from orbiting debris. a. late heavy bombardment b. formation of highlands c. cooling of interior d. formation of lowlands e. came together from orbiting debris 71. The arrow in the picture above is pointing to __________. a. the lunar highlands b. the lunar lowlands 72. Ultraviolet light has a __________ wavelength compared to infrared light. a. longer b. shorter c. same 73. X-rays has a __________ speed compared to gamma rays. a. higher b. lower c. same 74. Radio waves have __________ energy compared to visible light. a. higher b. lower c. same 75. Earth’s surface is primarily heated by which two forms of energy? a. ultraviolet and visible b. ultraviolet and infrared c. x-ray and ultraviolet d. visible and radio e. visible and infrared 76. Which of the following is a primary characteristic of greenhouse gases? a. They absorb more molecules in the atmosphere than they give off. b. They concentrate sunlight as it travels through the atmosphere. c. They absorb some forms of light but allow other forms of light to pass through. d. They permanently trap some forms of light in the atmosphere. e. They absorb more light than they give off. 77. The more greenhouse gases, the __________ a planet. a. colder b. hotter c. greenhouse gases have no effect on temperature 77. What was the Amazonian (late period) on Mars like? a. cooled interior, no liquid water on surface, no volcanism b. hot interior, liquid water on surface, lots of volcanism c. cooling interior, water freezing, volcanism decreasing 78. Which feature did NOT form on Mars during the Noachian (early period)? a. stream beds b. volcanoes c. sand dunes d. craters e. divergent ridges 79. Which rocks types can you find on the surface of Mars? a. igneous b. sedimentary c. metamorphic d. two of the above (sedimentary and igneous) e. all three rocks types 80. How does Mars’ current atmosphere compare to Earth’s atmosphere? a. it is nearly 100 x thicker b. it is about the same thickness c. it is nearly 100 x thinner 81. Mars was warmer in the past because a. it was closer to the Sun b. the Sun was brighter c. its atmosphere had more oxygen d. the greenhouse effect was stronger 82. Rank the planets’ surface temperatures from hottest to coldest: a. Mars > Venus > Earth b. Earth > Venus > Mars c. Venus > Earth > Mars 83. Match the following terms with the process that creates them: aurora, magnetic field, great red spot, belt-zone circulation, rings a. rotating liquid hydrogen magnetic field b. collision and/or ripping apart of moons rings c. long lived storm great red spot d. solar wind particles interacting with the magnetic field and atmosphere aurora e. winds driven by rapid rotation belt-zone circulation 84. Which best describes the composition of Jupiter’s atmosphere? a. 61% nitrogen and 39% oxygen d. 86% hydrogen and 13% helium b. 52% hydrogen and 48% helium e. 100% hydrogen c. 93% helium and 7% hydrogen 85. Why is it inaccurate to call Jupiter a gas giant? a. it is mostly liquid water b. it is mostly liquid hydrogen c. it is mostly frozen ices d. it is mostly solid rock e. it is about half gas and half solid rock 86. Uranus is blue because of a. methane clouds in the atmosphere d. liquid water on the surface b. methane liquid on the surface e. nitrogen clouds in the atmosphere c. frozen water ice on the surface 87. Jupiter would not have auroras if it did not have a. liquid iron in the core. b. a liquid water ocean under the atmosphere. c. cloud layers of ammonia, ammonium hydrosulfide, and water vapor. d. liquid hydrogen in the center. e. rings. 88. Why do we NOT see clouds of ammonia, ammonium hydrosulfide, and water vapor on Uranus? a. the atmosphere of Uranus is too warm for these clouds to form b. the atmosphere of Uranus to too cold for these clouds to form c. there is none of these compounds in Uranus’ atmosphere d. the clouds layers are there, they are just too deep down to see 89. Match the following Jovian moons with their descriptions: Io, Europa, Ganymede, Callisto, Titan. a. icy surface with an ocean close to the surface underneath Europa b. most volcanically active body in the solar system Io c. old cratered surface, undifferentiated interior Callisto d. icy surface with an ocean deep below the surface underneath Ganymede e. lakes and rain of liquid methane Titan 90. Which features would you find forming on Titan? a. craters b. volcanoes c. stream beds d. more than one of the above (craters and stream beds) e. none of the above 91. Which features would you find forming on Callisto? a. craters b. volcanoes c. stream beds d. more than one of the above e. none of the above 92. Why is Io the most geologically active of all of Jupiter’s moons? a. it is the biggest b. it has the most eccentric orbit c. it is the closet to Jupiter d. it is the densest e. it has the most radioactive elements 93. If a moon is smaller, then it will experience __________ tidal heating. a. more b. less c. the same amount of 94. Which moon do you expect to experience the least tidal heating? a. a small moon far from a small planet b. a small moon close to a small planet c. a large moon close to a small planet d. a large moon far from a small planet The diagram below shows the radial velocity curve for an exoplanet orbiting its star. Questions 95-97 refer to this diagram. Remember that by convention, positive radial velocities are away from the Earth. 95. When the planet is at position I, which way is the star moving? a. towards the top of the page b. towards the bottom of the page c. towards the left d. towards the right 96. When the planet is at position K, what Doppler shift does the star experience? a. redshift b. blueshift c. no Doppler shift 97. Position D of the radial velocity curve corresponds to what planet position? a. L c. J b. K d. I The diagram below shows the light curve for two stars; one star is orbited by “planet A” and the other star is orbited by “planet B”. Questions 98-100 refer to these diagrams. 98. Which position corresponds to the planet being located on the opposite side of the star from the observer? a. A c. C b. B d. D 99. Which position corresponds to the planet going from being not in front of the star to in front of the star? a. A c. C b. B d. D 100. Which planet is bigger? a. planet A b. planet B c. they are the same 101. The habitable zone around a star that is hotter than our Sun will be a. closer to its star than the zone around our Sun is. b. further from its star than the zone around our Sun is. c. the same distance from its star that the zone around our Sun is. 102. Scientists estimate that there are __________ of earth-sized exoplanets in their stars’ habitable zones in our galaxy. a. just one (the Earth) b. tens c. thousands d. tens of thousands e. billions 103. True or False: The habitable zone around a star stays the same with time. a. True b. False 104. Most of the exoplanets that have been found a. are bigger than the Earth and orbit further than 1 AU. b. are bigger than the Earth and orbit closer than 1 AU. c. are smaller than the Earth and orbit further than 1 AU. d. are smaller than the Earth and orbit closer than 1 AU. 105. A planet orbiting a star that is much smaller than our Sun is more likely to have a. life that is less advanced than life on Earth b. life that is more advanced than life on Earth c. life that is similar to life on Earth 106. True of False: If a planet is located within its stars habitable zone, it has liquid water on its surface. a. True b. False Short Answer 1. Circle the characteristics that apply to a planet. orbits the sun big enough to be round cleared orbit of debris Circle the characteristics that apply to a dwarf planet. orbits the sun big enough to be round cleared orbit of debris Circle the characteristics that apply to an asteroid. orbits the sun big enough to be round cleared orbit of debris orbits between 2 and 5 AU orbits between 40 and 500 AU made of rock and ice made of rock Circle the characteristics that apply to a KBO. orbits the sun big enough to be round cleared orbit of debris orbits between 2 and 5 AU orbits between 40 and 500 AU made of rock and ice made of rock 2. How many Earths could you fit in the distance between Saturn’s and Jupiter’s orbits? Show your work! Saturn is 9.5 AU from the Sun, and Jupiter is 5.2 AU from the Sun. Thus the distance between their orbits is 9.5 AU – 5.2 AU = 5.3 AU. You can fit 110 Suns in 1 AU, so this is 5.3 AU x 110 Suns / 1 AU = 583 Suns in 5.3 AU. You can fit 110 Earths in 1 Sun, so this 583 Suns x 110 Earths / Sun = 64,130 Earths in 5.3 AU. 3. In the table below, fill in the blank spaces in the first row to indicate the two characteristics of a good hypothesis. Then complete the table by indicating whether each hypothesis fulfills the characteristics or not. Good TESTABLE? EVIDENCE-BASED? Hypothesis Hypothesis? (write yes or no) (write yes or no) (write yes or no) 1. The planets are evenly spaced in Yes No No distance from the Sun. 2. There are planets that are bigger than Yes Yes Yes the Earth. 3. Humans have a soul that survives No No No death. 4. Sweatpants are more comfortable No No No than jeans. 4. The diagram below illustrates the orbit of a planet around the Sun. Four segments of the orbit are shown (A, B, C, D) and the area swept out as the planet travels each segment is also shown. Assume the planet travels counterclockwise. a) Which pair of segments does the planet take the same amount of time to travel B and D (same area) b) Rank the time that the planet takes to travel each segment from longest to shortest. C, B=D, A (biggest area to smallest area) c) Rank the speed that the planet travels each segment from fastest to slowest. A, B, D, C (closest to sun to furthest from sun) d) For each segment, indicate whether the planet is slowing down, speeding up, or both. A and B – speeding up (getting closer to the sun) D – slowing down (getting further from the sun) C – both (first getting further from the sun, then getting closer) 5. The figure below shows four planets with a location (A, B, C, and D) marked on each planet. The locations are all at the same distance from the equator (20 degrees). a) Which locations are experiencing summer? B, C and D b) Which locations are experiencing winter? None! c) Which locations are experiencing daytime? B and C d) Rank the locations from the one that will experience the most seasonal change to the one that will experience the least. C, B, D, A 6. For each diagram below, indicate a) the moon phase shown and b) the time of day shown. A – third quarter, midnight B – waxing gibbous, 9 pm C – waning crescent, noon D – new, 6 am 7. The graph below illustrates the temperature at different distances from the Sun during the formation of the solar system. a) Draw a line in the graph, like the one provided, to represent the temperatures during the time of formation for a solar system with a warmer star. b) For the line you drew, indicate at what distances you would expect terrestrial planets and at what distances you would expect Jovian planets. Terrestrial Planets = 0.1 AU to 3.75 AU (distances warmer than 373K). Jovian Planets = 5 AU to 50 AU (distances colder than 273 K). 8. You observe a planet with old, cratered divergent ridges and lava flows. There is no evidence of stream beds or sand dunes. What can you infer about this planet (e.g. Does it/did it once have an atmosphere? Liquid water on the surface? A hot, partially molten interior? Plate tectonics?) -This planet used to have plate tectonics and a hot interior, but it doesn’t now. -It never had an atmosphere or liquid water on the surface. 9. The picture below shows four planets. Light gray represents ice with a density of 1000 kg/m^3, medium gray represents rock with a density of 3000 kg/m^3, and black represents metal with a density of 8000 kg/m^3. For each planet, give an estimate of the bulk (average) density. Then rank the densities of the planets from greatest to least. A: between 1000 and 3000 kg/m^3; about 2500 kg/m^3 B: between 3000 and 8000 kg/m^3; about 7000 kg/m^3 C: 3000 kg/m^3 D: between 3000 and 8000 kg/m^3; about 4000 kg/m^3 B>D>C>A 10. The diagram below shows an area of the moon with 5 labeled events. Put the events in order of oldest (formed first) to youngest (formed last). If you can’t tell the order between events, put equal signs (like you did for the cratering homework). C, lava, A=D, B 11. A student says, “I understand how impact recurrence intervals work. If an impact has a recurrence interval of 20 years, that means that each year there is a 1% chance that an impact of this size will occur. It doesn’t matter when the last impact was, because each year is independent of the previous year; the chance is always the same. Do you agree/disagree and why? I partially agree and partially disagree. I agree that it doesn’t matter when the last impact was – each year is independent from the previous year because impacts are statistically random. Thus it is true that the chance of an impact each year is always the same. However, the chance is dependent upon the recurrence interval. 1% is only the chance for an impact that has a recurrence interval of 100 years. The impact in this question has a recurrence interval of 20 years, so the chance is 1/20 = 5%. 12. Why is the giant impact hypothesis for the formation of the moon considered a better hypothesis than the capture hypothesis? The giant impact hypothesis suggests that the moon formed from the debris thrown off when a large asteroid collided with the Earth. The capture hypothesis suggests that the moon was an asteroid that got captured by the Earth’s gravity. The giant impact hypothesis can explain why the moon and the Earth appear to have formed in the same location, why the moon is less dense than the Earth, why the moon’s rocks have less gases than the Earth’s rocks do, and why the moon’s orbit is tilted relative to the Earth’s orbit. The capture hypothesis, however, can only explain the last observation (why the moon’s orbit is tilted relative to the Earth’s orbit). It cannot explain why the moon and Earth appear to have formed in the same location, why the moon is less dense than the Earth, or why the moon’s rocks have less gases than the Earth’s rocks do. 13. A student says, “I understand now how the greenhouse effect works. The surface of the Earth (or a planet) absorbs visible light from the Sun. This causes the surface to heat up and emit infrared light. As the infrared light tries to escape, it is absorbed and permanently trapped by the greenhouse gases.” Do you agree/disagree and why? I agree with the first part – it is true that a planet’s surface absorbs visible light from the Sun and emits infrared light in response. However, it is not true that the outgoing infrared light is permanently trapped; it is only temporarily trapped. Eventually the infared light will make its way out, but the more greenhouse gases there are, the longer that will take, and the warmer the planet will be. 14. A student says, “I think that the reason Mars is so cold today is that it is too far from the Sun. If it had been closer to the Sun, like Earth, it would still have a warm atmosphere and liquid water.” Do you agree/disagree and why? I disagree. Even if Mars were closer to the Sun, it would still not be large enough to remain geologically active. The interior would still cool, volcanism would stop, and the magnetic field would die. Without the magnetic field to protect the atmosphere from the solar wind, the atmosphere would thin and cool down as a result of fewer greenhouse gases. The only way that Mars could still be geologically active today is if it were bigger. 15. The diagram below shows the temperature profile through the atmosphere of a hypothetical Jovian planet. What clouds would you observe on this planet, and at what height would you observe these clouds? Recall that methane clouds condense at 90 Kelvin, ammonia clouds at 130 Kelvin, ammonia hydrosulfide clouds at 200 Kelvin, and water vapor clouds at 270 Kelvin. -no methane clouds -no ammonia clouds -no ammonia hydrosulfide clouds -water vapor clouds at -120 km 16. The table below shows data for five planet-moon systems. Rank the systems from the moon which will experience the most tidal heating to the moon which will experience the least tidal heating. Provide a reasoning for your answer. Moon Mass Planet Moon- Semi- (in terms of Mass Eccentr Planet Major Axis the Earth's (in terms icity System (AU) moon) of Jupiter) A 1.5 0.5 0.1 0.006 AU B 2.5 1.5 0.3 0.002 AU C 2 1 0.2 0.004 AU D 2 1.5 0.0 0.004 AU E 1.5 1 0.1 0.006 AU Greater tidal heating will correspond to a larger moon mass, a larger planet mass, a higher eccentricity, and a smaller semi-major axis (e.g. closer distance). Zero eccentricity means no tidal heating. Thus: B > C > E > A > D. B has a larger moon mass, a larger planet mass, a higher eccentricity, and a closer distance than C. C has a larger moon mass, a higher eccentricity, and a closer distance than E. E has a larger planet mass than A. D has zero eccentricity, and thus experiences no tidal heating. 17. The below picture shows a light curve for a star with two transiting planets, one bigger and one smaller. a. Use the letter “A” to label a location where just the bigger planet is in front of the star. b. Use the letter “B” to label a location where just the smaller planet is in front of the star. c. Use the letter “C” to label a location where both planets are in front of the star. d. Which planet is closer to the star – the bigger one or the smaller one? the bigger one 18. A student says, "I understand how the habitable zone works. If a planet is in the habitable zone, there might be liquid water on the surface (as long as the planet is also the right size). And if there is liquid water on the surface, there could be life. However, if a planet is located outside of the habitable zone, there is no way there could possibly be life on the surface.” Do you agree or disagree with this student and why? I agree with the first part, it is true that: “If a planet is in the habitable zone, there might be liquid water on the surface (as long as the planet is also the right size). And if there is liquid water on the surface, there could be life.” However, I disagree that just because a planet is located outside of the habitable zone, it has a 0% chance of life. There might not be water on the surface, but there could be water underneath the surface (like on Europa). It is possible life could be found there. Additionally, it is possible that there are forms of life that don’t need liquid water, but use other liquids instead. We just don’t know.