Q&A Hero

Q: When strong solar winds are displaced poleward by our magnetic fields, we get A) the Van Allen radiation belts. B) intense auroral displays. C) sunspots. D) hurricanes in the tropics. E) droughts and dust bowls in the American West.

Q: The presence of a magnetic field is a good indication that A) the Earth's interior is similar to Mercury's, as both have fields. B) a huge iron meteorite lies somewhere high up in the mantle, not in the core. C) the Earth has a liquid metal outer core, spinning rapidly as it rotates. D) the Earth's interior must be completely molten to the center. E) the Earth's interior has had time to solidify, with a rigid bar magnet created.

Q: What is true of the lunar highlands? A) They are found on the Moon's northern hemisphere. B) They are less heavily cratered than the mare. C) They are the darker regions of the Moon seen with the naked eye. D) They are younger than the darker mare. E) They are the oldest part of the lunar surface.

Q: The rate of cratering in the lunar highlands shows us that A) they must be younger than the older, darker mare. B) they range from 4.6 - 4.4 billion years old, on average. C) the largest impacts are the youngest, such as Copernicus and Tycho. 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.

Q: Which of these age ranges best describes the lunar maria? A) 8.6 - 6.0 billion years B) 3.9 - 3.2 billion years C) 2.5 - 1.0 billion years D) 100 - 65 million years E) a few million years to present lava flows seen erupting

Q: The lunar mare are found A) uniformly all over the Moon. B) mainly on the near side. C) mainly on the far side. D) only in the dark areas of the lunar poles, where water is not boiled away. E) only as layered rocks, since the original water was lost long ago.

Q: The far side of the Moon was first mapped A) by Galileo in 1610 with his first telescope. B) by the Apollo astronauts on the first orbit of the Moon with Apollo 8. C) by early Russian spacecraft. D) by NASA with its Lunar Orbiters in the 1960s. E) by William Herschel with his large reflectors in the early 1800s.

Q: Today, an average lunar moonquake releases about as much energy as A) an atomic bomb. B) a firecracker. C) the Mount St. Helens eruption. D) a major U.S. city uses in 1 year. E) the most powerful earthquake ever recorded.

Q: Which of these is not a result of plate tectonics? A) the Grand Canyon B) the Andes C) the Mid-Atlantic Rift D) the San Andreas Fault E) the Philippine Trench

Q: Which statement about seismic waves is true? A) Only S waves can travel through liquid. B) P waves travel faster, and thus arrive sooner than do the S waves. C) In the shadow zones, neither type is observed. D) S waves can travel though the outer core, but P waves cannot. E) On the far side of the Earth, only the S waves on the surface can be detected.

Q: Seismic waves are most useful for mapping A) the surface of Venus with Magellan. B) the surface of Mars with Global Surveyor. C) the Earth's core and mantle. D) the density of the hydrosphere. E) the depths of the oceans.

Q: In noting that the Earth is "differentiated," we mean that A) the density increases as you descend downward toward the core. B) the Earth is very different than any other planet we study. C) the Earth's magnetic field varies at different locations on the globe. D) the density of oceanic basalt is less than that of granite on the mountain tops. E) the radioactive heating in the core is increasing with time.

Q: The atmospheric gases primarily responsible for our greenhouse effect are A) carbon monoxide and methane. B) hydrogen and helium. C) oxygen and carbon dioxide. D) argon and water vapor. E) water vapor and carbon dioxide.

Q: We determine the structure of the Earth's core using A) deep mine shafts. B) satellite imaging. C) radar and sonar. D) seismic wave data. E) magnetic resonance imaging.

Q: The average rate of erosion on the Moon is far less than on Earth because A) the crust of the Moon is much denser than the Earth's crust. B) the Moon is much younger than the Earth. C) the Moon lacks wind, water, and an atmosphere. D) the Moon's magnetic field protects it from the solar wind better than ours does. E) the Moon's mare long ago dried up, so there is no more wave erosion there.

Q: After the Lunar Reconnaissance Orbiter (LRO) crashed into the moon, its sister spacecraft LCROSS detected an amount of water in the ejecta A) comparable to soggy ground on Earth. B) comparable to fertile soil on Earth. C) comparable to dried-up lake beds on Earth. D) less than is contained in desert sand on Earth. E) Actually, no water was detected at all.

Q: The major presence of water detected on the Moon is in A) the mare. B) the floors of deep craters in the polar regions, as ice deposits that never thaw. C) the flows of mud seen on the walls of some craters. D) the puffs of steam seen coming from some still active lunar volcanoes. E) faint clouds of ice in the thin lunar atmosphere.

Q: What is the average molecular speed of hydrogen (mass = 1) on Earth (temperature = 300 K)? A) 4.71 km/s B) 2.72 m/s C) 4.71 m/s D) 2.72 km/s E) None of the above

Q: Without the greenhouse effect operating in our atmosphere, A) we would not have to worry about any warming problems in the future. B) Earth would have an average temperature of -23 degrees Celsius. C) the ice in the polar regions would have melted long ago. D) the ozone layer would not be weakening. E) the Earth would have become much more like Venus long ago.

Q: Which of these gases is least abundant in our atmosphere? A) hydrogen B) carbon dioxide C) argon D) nitrogen E) oxygen

Q: In what part of our atmosphere do we live? A) troposphere B) stratosphere C) mesosphere D) ionosphere E) exosphere

Q: The critical part of the atmosphere for protecting life on the ground from excessive ultraviolet radiation is the A) hydrosphere. B) troposphere. C) ozone layer. D) stratosphere. E) ionosphere.

Q: Almost all of our atmospheric gases lie in the A) ionosphere. B) stratosphere. C) troposphere. D) ozone layer. E) mesosphere.

Q: What is true of the Moon's orbital and rotational periods? A) The rotational period is longer. B) The orbital period is longer. C) The rotational period varies with the Moon's phase. D) They are equal. E) The orbital period is greatest at full moon.

Q: The smallest high tides occur when the Moon phase is A) first or third quarter. B) full. C) new. D) waxing or waning crescent. E) waxing or waning gibbous.

Q: The Moon's near side always faces Earth due to A) the Sun's gravity. B) Earth's magnetic field. C) Earth's tidal force. D) conservation of angular momentum in the solar nebula. E) the solar wind.

Q: At what phase are the tides least noticeable? A) new moon B) full moon C) third quarter D) waxing crescent E) waning gibbous

Q: What is true of spring tides? A) The third quarter moon would be high overhead at dawn. B) The difference between low and high tides would be greatest. C) There would be one high and one low tide each day. D) The Moon's phase will be first quarter. E) The difference between low and high tides would be smallest.

Q: At what phase would you expect to find extremely high and low tides? A) new moon B) first and third quarter C) full moon D) both new and full moons E) Moon phases do not impact the tides.

Q: Which of the following layers of the Earth is unique among the terrestrial planets? A) hydrosphere B) ionosphere C) mantle D) crust E) core

Q: Today most scientists favor the capture theory of the Moon's origin, since it would explain why the Moon still orbits in the ecliptic plane, as do other planets.

Q: The crust on the near side of the Moon is on average thinner than the crust on the far side, due to our tidal pull on the Moon.

Q: The lunar mare radioactively date back to 4.6 billion years, at the origin of the Moon, hence their dark color due to this aging.

Q: The lunar highlands appear brighter than the mare, because these highlands are due to meteor impact that completely avoided the mare.

Q: The lunar mare are younger than any of the craters that sit in them.

Q: The Van Allen belts are cloud layers in the jet streams of the stratosphere, similar to the belts that Galileo saw on Jupiter.

Q: The Moon and the crustal rocks of Earth are similar in density.

Q: Most lunar craters are volcanic in origin.

Q: Early telescopic observers thought the lunar mare were seas of water; today we know they are not liquid water but molten basalt, long ago frozen out.

Q: When plates collide, they fuse together and come to rest.

Q: In the past, most of the landmass on Earth was concentrated in a single, large continent.

Q: There is no evidence for plate tectonics on the Moon today.

Q: Seismic P-waves can be detected worldwide from any strong epicenter.

Q: Samples of the Earth's molten outer core come directly through the mantle, pour out of volcanoes, and can be studied in labs.

Q: A seismograph could register P but not S waves from an epicenter on the opposite side of the Earth.

Q: One source of the energy for volcanism and plate tectonics is radioactivity in the Earth's interior.

Q: Seismic S-waves can travel through Earth's liquid outer core.

Q: Seismic P-waves can travel through both solid and liquid materials.

Q: The Earth's inner core is about the same temperature as the surface of the Sun.

Q: The Moon's lower density indicates it has a smaller concentration of iron in its core, as does the absence of a lunar magnetic field.

Q: The Moon's surface gravity is only half the Earth's.

Q: The three most abundant gases in our atmosphere are nitrogen, oxygen, and argon.

Q: The ozone layer lies above the troposphere and below the mesosphere.

Q: The continuing rise of carbon dioxide concentration in our troposphere is leading to worldwide cooling as dry ice forms at the poles.

Q: Weather occurs in the troposphere.

Q: Greenhouse gases in our atmosphere trap just enough heat to keep the Earth's oceans liquid.

Q: Due to its larger mass, the Sun's gravitational effect on Earth's tides is greater than the Moon's.

Q: In most places on the seacoast, there are two high and two low tides a day.

Q: Spring tides occur only at new Moon, when the Moon and Sun pull together.

Q: The Earth and Moon always keep the same side towards each other.

Q: The Moon keeps one side facing the Earth because it doesn't rotate on its axis.

Q: The tidal pull of the Moon is an example of a differential force, as the near and far sides of the Earth do not experience the same gravitational pull of the Moon.

Q: Neap tides occur at first and third quarter phases of the Moon.

Q: On average, the Moon orbits Earth from a distance of about 30 Earth radii.

Q: The Earth's hotter, inner core is liquid and its cooler, outer core is solid.

Q: Compared to Earth, the Moon lacks a hydrosphere, atmosphere, and a magnetosphere.

Q: Our Earth is about four times larger than the Moon in diameter.

Q: At what point does the accretion process turn a clump of debris into a planetesimal?

Q: Describe the orbits of the Trojan asteroids.

Q: What class of asteroids is a threat to Earth and other terrestrial planets? Why?

Q: Contrast meteoroids and asteroids.

Q: What do long period comets tells us about the structure of the Oort Cloud?

Q: How do we believe the Barringer crater formed?

Q: Describe the orbits of the Kuiper Belt bodies.

Q: Name the four principal types of solar-system debris; pair them up in terms of composition.

Q: Contrast the orbits of asteroids and Kuiper Belt bodies.

Q: Contrast the composition of stony and iron meteorites.

Q: How do the atmospheres of terrestrial worlds compare with the jovians?

Q: Contrast the densities of the terrestrial and jovian planets.

Q: Name three differences between terrestrial and jovian planets.