Name: Period: Date: Astronomy Ch. 8 The Moon and Mercury MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) The best way to find the exact distance to the Moon is to: A) measure its exact size in the telescope. B) make parallax measurements from observatories on opposite sides of the Earth. C) bounce lasers off the retroreflectors left on the surface by the Apollo landings. D) use radar reflection times, about 2.56 second. E) use stellar occultations for precise timings of the moon's position. 1) 2) What is the reason that it is so difficult to view Mercury from Earth? A) Mercury is often hidden by the Moon. B) Mercury is very small. C) Mercury can't be seen at night. D) Mercury is very dim. E) Mercury is always very close to the Sun. 2) 3) Mercury is very hard to observe from Earth because: A) it always appears as only half lit from Earth. B) it never gets more than 28 degrees from the Sun's glare. C) its barren surface reflects too little sunlight; it is almost invisible always. D) its elliptical orbit causes it to change speed unpredictably. E) its very rugged surface does not allow radar to bounce back to Earth. 3) 4) From Earth, due to their motions and the fact that the Sun lights only a portion of each surface, both Mercury and the Moon: A) appear to go through phases. B) always have the same side facing Earth. C) always look full from Earth. D) pass through Earth's shadow. E) appear to be half-lit by the Sun. 4) 5) Mercury experiences extreme high and low temperatures between night and day because: A) its oceans are much hotter than ours. B) it has no atmosphere to moderate temperatures over the globe. C) it is so close to the Sun. D) its dense atmosphere creates a runaway greenhouse. E) Mercury has no axial tilt, with its equator always exposed to direct sunlight. 5) 6) In size, Mercury is intermediate between: A) Ceres and Pluto. B) Earth and Venus. C) Pluto and the Moon. D) Mars and Earth. E) the Moon and Mars. 6) 1
7) How do the atmospheres of the Moon and Mercury compare? A) They are about equal, each only 1% as dense as ours. B) As no spacecraft has yet landed there, no information exists about Mercury's. C) The cooler Moon retains a thicker nitrogen atmosphere. D) Mercury's is much denser, like Venus, with much carbon dioxide. E) Neither body has a permanent atmosphere. 7) 8) If the Earth's surface temperature were increased to that of Mercury's day side, then: A) we would lose most of our water vapor into space. B) little would happen, as the earth is still the same mass and surface gravity. C) the evaporating oceans would thicken the atmosphere greatly. D) the Earth would, like Mercury, lose all its atmospheric gases. E) the erupting volcanoes would greatly increase the carbon dioxide greenhouse. 8) 9) Which of the following is NOT a factor in determining whether a body in the solar system retains an atmosphere? A) axial tilt B) escape velocity C) rotation rate D) composition and weight of the gases E) distance from the Sun 9) 10) Comparing the densities of the Moon and Mercury, we find: A) that density increases as we go outward from the Sun. B) the Moon's is similar to Earth's crust, while Mercury's is similar to the entire Earth. C) the Moon is slightly denser than Mercury. D) similar in surface appearance, they are also similar in density. E) both are much denser than our water-covered planet. 10) 11) One of the effects of Mercury's very slow spin is A) extreme variations in its surface temperature. B) wind patterns that are slow, but global in size. C) large variations in the size of its polar cap. D) an intensely powerful magnetic field. E) tectonic activity. 11) 12) The lunar mare are found: A) almost entirely on Earth side, where the crust was thinner. B) almost entirely on the far side, which was more likely to be hit. C) anywhere large meteor impacts created deep basins. D) mainly in the south polar region, where the largest impact occurred. E) not at all, since no liquid water really exists on the Moon. 12) 13) The lunar highlands are: A) formed by volcanic eruptions, much like our Andes. B) made of lighter colored, younger rocks than the mare. C) brighter than the mare, since they are covered with reflective glass from the rays. D) formed by plate tectonics, like the Earth's Himalayas. E) more rugged, heavily cratered, and older than the lunar mare. 13) 2
14) The youngest features visible with telescopes on the Moon are: A) the bright polar caps of new ice. B) the darkest regions of the mare. C) the volcanoes seen erupting in the highlands. D) the scarps recently created by tectonic activity. E) the craters sitting atop the mare. 14) 15) What is true of the lunar highlands? A) They are the darker regions of the Moon seen with the naked eye. B) They are less heavily cratered than the mare. C) They are the oldest part of the lunar surface.. D) They are found on the Moon's northern hemisphere. E) They are younger than the darker mare. 15) 16) The lunar mare are radioactively dated at: A) 4.2-3.9 billion years old, comparable to the adjacent highlands. B) 3.5-2.5 billion years old, similar to the formation of our own oceans. C) less than a billion years old, the most recent additions to the Moon. D) 4.6 billion years old, forming first among the lunar features. E) 3.9-3.2 billion years old, forming after most of the bombardment was over. 16) 17) To measure how Mercury spins, astronomers sent to Mercury and used the Doppler shift to determine how fast it was rotating. A) a satellite B) radar beams C) laser beams D) probes E) a single frequency radio signal 17) 18) What did radar astronomers find in the polar regions of Mercury? A) auroral displays much like Earth's B) polar caps of dry ice that vary seasonally, much like Mars C) water ice that never melts in the deep craters D) rift valleys E) large mare basins, such as near our Moon's south pole 18) 19) Which statement about the rotations of the Moon and Mercury is FALSE? A) On Mercury, three days exactly equal two years. B) On the Moon, each "day" lasts about 15 earth days of constant sunlight. C) Our Moon is in a 1:1 synch with the Earth, keeping the same side toward us. D) Like our Moon, Mercury does not rotate at all, keeping the same side facing the Sun. E) Mercury is in the 3:2 synch with the Sun, with the same side Sunward at perihelion. 19) 20) How does Mercury's rotation relate to the Sun? A) Its year is much shorter, only 88 days, than its slow rotation of 243 days on its axis. B) It always keeps one face tidally locked toward the Sun, as our Moon does with us. C) Its rotation rate is 2/3 as long as its year, due to tidal resonances. D) Its day is the same length as its year. E) It does not spin at all, being tidal stopped by the solar tides. 20) 3
21) What causes Mercury's 3:2 spin-orbit resonance? A) the planet's very eccentric orbit B) the planet's closeness to the Sun C) the planet's high density D) tidal torques operating on the planet E) All of the above are factors. 21) 22) Mercury presents the same side to the Sun A) all the time, just like our Moon. B) every other orbit. C) twice every orbit. D) every third orbit. E) every 12 hours. 22) 23) What is true of the Moon's orbital and rotational periods? A) The rotational period is longer. B) The rotational period varies with the Moon's phase. C) The orbital period is longer. D) They are equal. E) The orbital period is greatest at full moon. 23) 24) The chief erosive agent now on the Moon is: A) lava flows welling up in the mare. B) volcanic vents in the rugged highlands. C) rain from cometary debris melting as it enters the moon's atmosphere. D) lunar ice melting and refreezing in the polar regions. E) the rain of micrometeorites chewing up the regolith. 24) 25) The rate of cratering: A) has recently increased with more collisions in the asteroid belt. B) has remained constant over the last 4.6 billion years. C) fluctuates over time, with massive bodies occasionally coming in from the Oort Cloud. D) shows that most interplanetary debris was swept up soon after the formation of the solar system. E) shows that large asteroid impacts are more common now than in the past. 25) 26) The rate of cratering in the lunar highlands shows us that A) they range from 4.6-4.4 billion years old, on average. B) the largest impacts are the youngest, such as Copernicus and Tycho. C) they must be younger than the older, darker mare. D) the oldest rocks are at least as old as the mare, but some craters are much younger. E) most of the asteroids must have hit the Moon, not the earth. 26) 27) The average rate of erosion on the Moon is far less than on Earth because A) the Moon's mare long ago dried up, so there is no more wave erosion there. B) the Moon's magnetic field protects it from the solar wind better than ours does. C) the Moon is much younger than the earth. D) the crust of the Moon is much denser than the earth's crust. E) the Moon lacks wind, water and an atmosphere. 27) 4
28) Which type of feature is the best evidence of lunar volcanism? A) vents seen erupting in the mountainous highlands B) rays around the latest eruptions C) the Orientale Basin D) craters all over the Moon E) rilles associated with lava flows accompanying the mare formation 28) 29) The spacecraft which reveal the possibility of lunar ice are: A) Lunar Orbiter and Rover. B) Lunar Ranger and Surveyor. C) Vikings 1 and 2. D) Apollos XI and XVII. E) Clementine and Lunar Prospector. 29) 30) Mercury's surface most resembles that of which other body? A) Mars B) Venus C) Earth D) Io E) Moon 30) 31) Which of these features is attributed to the shrinking of Mercury's core? A) rilles B) mare C) scarps D) rays E) craters 31) 32) Almost all we know about Mercury has come from: A) telescopic observations for Earth near greatest elongations. B) the Hubble Space Telescope's high resolution images. C) radar imaging of its rugged surface. D) the three flybys of Mariner 10. E) the messenger orbiter. 32) 33) Mercury and the Moon appear similar, but we note that: A) Mercury has "weird terrain" opposite its huge Caloris basin. B) Mercury does not always keep the same face toward the Sun, while the Moon does have the Earthside always facing us. C) the lunar mare are darker than Mercury's intercrater plains. D) Mercury has striking lobate scarps due to the shrinking of its core. E) All of the above are correct. 33) 34) The scarps on Mercury were probably caused by A) the interior cooling and shrinking. B) tectonic activity. C) volcanism. D) a tidal bulge. E) meteorite bombardment. 34) 5
35) Mercury's surface most resembles which of these? A) Venus' polar regions B) the earth's deserts C) the lunar far side D) Mars' deserts E) the lunar mare 35) 36) Mercury's Caloris basin is aptly named, since: A) it is the region on Mercury looking much like our own "painted desert". B) it is the largest impact basin found in the solar system. C) it is the hottest region, turning to face the Sun when Mercury is at perihelion. D) it is always pointed directly at the Sun. E) it is the only such large basin on Mercury. 36) 37) The Moon's huge Mare Orientale basin has a twin on Mercury named: A) Mare Marineris. B) Valhalla. C) Caloris. D) the weird terrain. E) Galileo. 37) 38) Moonquakes on the Moon were detected by: A) seismographs attached to the Russian Lunar rovers. B) telescopic observations of lunar landslides. C) the radar observations over time from earth. D) laser beams reflected off mirrors left on the Moon by Apollo missions. E) the seismographs left these by the Apollo astronauts. 38) 39) What do moonquakes reveal about the Moon? A) It has a differentiated core, displaced away from us by the Moon's rotation. B) Its small, partially molten core has been pulled toward us by tidal forces. C) The Moon has been geologically dead throughout its entire history. D) The Moon is quite active, almost as much so as Jupiter's moon Io. E) It has a strong magnetic field generated by a large molten core. 39) 40) How does Mercury's magnetic field compare to our own? A) Like Mars and the Earth, it too has undergone polarity reversals. B) It is amazingly strong, comparable to our own. C) Like Venus, Mercury has no detectable magnetic field. D) It was predicted from Mercury's rapid rotation and molten core. E) It is 1/100th as strong as ours, but does deflect the solar wind to some degree. 40) 41) What two properties of Mercury imply that it is differentiated? A) its large average density and its surface features B) its magnetic field and its surface features C) its surface features and its size D) its size and magnetic field E) its large average density and its magnetic field 41) 6
42) The presence of a Mercurian magnetic field surprised the planetary scientists on the Mariner 10 team because A) Mercury is low in iron. B) Mercury lacks an iron core. C) Mercury spins to rapidly to produce a stable dynamo. D) it's still too hot for its core to have differentiated. E) the dynamo theory predicted that Mercury was spinning too slowly for one. 42) 43) Which of these theories seems to best explain the Moon's origin? A) Impact Theory B) Coformation Theory C) Capture Theory D) Fusion Theory E) Fission Theory 43) 44) What are the major factors that rule out the co-formation theory for the Moon-Earth system? A) Each body has a different density and a different chemical composition. B) Each body has different surface features and different atmospheric content. C) Each body has a different chemical composition and different atmospheric content. D) Each body has different chemical composition and different surface features. E) Each body has different atmospheric content and a different density. 44) 45) Which of these would support the capture theory of the Moon's origin? A) the retrograde orbit and large orbital inclination of Neptune's moon Triton B) the rings of all the jovians lying around their equators C) the Caloris basin on Mercury D) the Pluto-Charon system E) the four large moons of Jupiter orbit its equator 45) 46) The cratering of the lunar highlands shows us: A) they are like the Earth's continents, removed from the tectonic cycle of the mare. B) they are younger than the maria. C) they were made of more rigid lavas than the basalts that made the maria. D) they are older than the smoother maria. E) they have been unchanged for the last 4.6 billion years. 46) 47) How are the polar regions of Mercury and the Moon similar? A) Both seem to have ice pockets in the deepest, darkest crater floors. B) Both have bright dry ice polar caps, like Mars. C) Both have been hit by large comets that melted there. D) Both are covered by huge mare-type basins from impacts. E) Both have lakes of liquid water under their regolith. 47) 48) Mercury's evolution was different from the Moon's because: A) Mercury developed a dense atmosphere while the Moon never did. B) Mercury was subject to more intense asteroid bombardment than the Moon. C) dense Mercury had an iron core that shrank, creating the lobate scarps. D) Mercury was located farther from Earth, so experienced no tidal forces. E) Mercury developed a strong magnetic field to protect it from solar radiation. 48) 7
49) Both the Moon and Mercury are geologically inactive and have been that way for most of the history of the solar system. However, about 4 billion years ago, it is thought that A) the Moon's atmosphere dissipated. B) both bodies were covered in ice. C) the Moon differentiated. D) the Moon had more frequent and violent volcanic activity than Mercury. E) Mercury had more common volcanic activity than the Moon. 49) 50) Astronomers believe that the Moon did not differentiate to the same degree as Earth because: A) the meteors that hit the moon were lighter than those that hit us, so did not generate as much heat on the surface. B) the Moon was made of solid debris, not liquids like our hydrosphere. C) the less dense and smaller moon did not have as much radioactivity as the larger Earth in its core. D) the Moon was made of very different materials than our mantle and crust. E) the Moon was formed after the Earth was, so its radioactivity was less. 50) 8