Q&A Hero

Q: There is less ammonia in the atmospheres of Uranus and Neptune than in Jupiter or Saturn.

Q: Although it is almost the same size as Jupiter, Saturn's gravity is about 2.5 times less, because of Saturn's lower mass and density.

Q: Helium is more abundant on Saturn than on Jupiter.

Q: The Galileo probe into Jupiter's atmosphere found more water than expected.

Q: Although water and ammonia can produce Jupiter's white clouds, the complex coloration we observe in Jupiter's atmosphere requires more complex chemistry.

Q: The zonal flows giving rise to the belts and zones are similar to the jet streams in our own stratosphere.

Q: Jupiter's atmosphere looks uniform and calm, with no visible detail.

Q: Jupiter's Great Red Spot is similar to a hurricane on Earth except for its size.

Q: The axial tilts of Uranus and Neptune are similar.

Q: There is a clear relationship between the interior and atmospheric rotation rates of the jovian planets.

Q: The rotation of the magnetic fields of the jovian planets is believed to also give us the rotation rate of the planet's core.

Q: Jupiter's axial tilt is similar to that of Mercury, while Saturn's is more like ours.

Q: The equators of all four jovian planets rotate more rapidly than the polar regions.

Q: All four jovian planets spin faster than any of the terrestrials.

Q: Differential rotation is when a planet's equatorial and polar regions rotate at different rates.

Q: All four jovian planets are made primarily of hydrogen and oxygen.

Q: Saturn is less dense than water.

Q: Changes in the predicted motion of Uranus led to the search for an eighth planet.

Q: Like the discovery of Uranus, the finding of Neptune was accidental.

Q: When Cassini entered orbit around Saturn, it caused the planet's orbit to change.

Q: The Galileo probe was deliberately steered into Jupiter's atmosphere, ending its mission.

Q: Most of our detailed knowledge of the jovian planets comes from the Hubble Space Telescope.

Q: While Voyagers were probes that flew past in a few days, Galileo and Cassini are orbiters, designed to study Jupiter and Saturn over prolonged periods of time.

Q: Galileo's early telescopes revealed the four large moons of Jupiter, the rings of Saturn, and its large moon Titan.

Q: William Herschel was the discoverer of Uranus.

Q: All nine planets in the solar system have been visited by spacecraft.

Q: A gravitational assist, or slingshot, can be used to either speed up or slow down a spacecraft.

Q: Mars appears red due to ________ on its surface.

Q: As with the lunar mare and Earth's ocean basins, the chief rock in the low plains of Venus is ________.

Q: In age, the surface of Venus is much ________ than even the lunar mare.

Q: Unlike our Moon and Mars, all the impact craters found on Venus are ________ in size.

Q: Smooth rolling plains, modest highlands and lowlands, and no water describes the surface of ________.

Q: The most effective wavelengths to see through the clouds of Venus to the surface are ________.

Q: The surface of Mercury looks very similar to ________.

Q: ________ are great wrinkle marks on Mercury's crust, due to its core contracting.

Q: The clouds on Venus are made primarily of ________.

Q: Because of their low surface gravities, the Moon and Mercury lack ________.

Q: While featureless in visible light, we can see some detail in Venus' clouds using ________.

Q: Of all the planets, the axial tilt and rotation period of ________ is most like our own.

Q: The planet which shows us the widest range of surface temperatures between day and night is ________.

Q: The direction of the rotation of Venus is exceptional because it is in a ________ direction.

Q: The Sun's tidal pull has slowed Mercury's rotation down to a period ________ that of its year.

Q: The only two planets which can transit the Sun are ________.

Q: Compared to the orbits of Venus and Earth, the orbits of both Mercury and Mars have much ________ eccentricity.

Q: Of all the planets known in antiquity, ________ is the hardest to observe visually.

Q: Much of the water on Mars A) is thought to be in a layer of permafrost just below the surface. B) lies in shallow pools near the poles. C) is locked in the seasonal ice cap. D) is found in deep pools near the equator. E) is in the form of clouds.

Q: 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 spins too rapidly to produce a stable dynamo. C) it's still too hot for its core to have differentiated. D) the dynamo theory predicted that Mercury was spinning too slowly for one. E) Mercury lacks an iron core.

Q: The largest difference between Mars' northern and southern hemispheres is that A) the southern appears older, with more impact craters. B) the northern has all the outflows and must have been much hotter. C) the northern is higher overall, despite some high volcanoes in the south. D) the southern has a polar cap, but none ever forms in the north. E) the southern is much darker, with large mare-like basaltic lava flows.

Q: That the Tharsis region on Mars has so few craters A) proves tectonic activity is taking place. B) is due to the very low elevation of the region. C) suggests it is the youngest region on the planet. D) suggests it is at the center of a particularly strong magnetic field. E) is due to annual flooding and water erosion.

Q: What is true of Mars? A) Its magnetic field is stronger than Earth's B) Its atmosphere is mostly water vapor. C) Iron oxide on the surface is responsible for its reddish color. D) A pool of water was discovered by the Mars Rover. E) Definite microfossils have been found.

Q: Which of the following characterizes a shield volcano? A) It sits above a hot spot in the planet's mantle. B) It is formed by moving tectonic plates. C) It can erupt only briefly before being dragged off the hot spot. D) It cannot get as high as Mt. Everest before the thin crust starts slumping. E) It cannot grow very large, for it has a very short span of eruption.

Q: The name of the NASA mission(s) that landed on Mars in 1976 was A) Voyager. B) Magellan. C) Viking I and II. D) Venera 14. E) Galileo.

Q: We have not yet found meteoroids and meteorites derived from A) Venus. B) the Moon. C) Mars. D) asteroids. E) comets.

Q: The deepest depression found on the surface of Mars is the A) Mariana Trench. B) Caloris basin. C) Valles Marineris rift. D) Hellas Basin. E) Mare Crisium.

Q: Valles Marineris is the most striking example of a(n) A) impact crater. B) shield volcano. C) oceanic trench. D) rift valley. E) scarp.

Q: Like Olympus Mons, volcanoes on Venus A) form where continental plates collide. B) are much larger than typical volcanoes on Earth. C) have been extinct for billions of years. D) only form at the equator. E) are shield volcanoes.

Q: Which statement is true of Venus' surface? A) There are two continent sized uplands. B) It has remained unchanged for billions of years. C) Atmospheric pressure is very low. D) There is an extensive hydrosphere. E) There are no shield volcanoes.

Q: What percentage of the surface of Venus could be characterized as continental-sized highlands? A) less than 10% B) about 30%, like the Earth C) 45% D) 75% E) 100%

Q: The surface of Venus can be observed with A) the Mt. Wilson 100" telescope. B) radar observations. C) most amateur telescopes. D) the Hubble Space Telescope. E) All of these have provided detailed observations about the surface of our sister planet.

Q: Our most detailed maps of Venus come from A) the Magellan space probe. B) the Hubble Space Telescope. C) direct observation from Earth-based optical telescopes. D) manned landings. E) Earth-based radio telescopes.

Q: What did radar astronomers find in the polar regions of Mercury? A) rift valleys B) large mare basins, such as near our Moon's south pole C) temperatures cold enough to allow thin sheets of water ice D) polar caps of dry ice that vary seasonally, much like Mars E) auroral displays much like Earth's

Q: The scarps on Mercury were probably caused by A) tectonic activity. B) meteorite bombardment. C) a tidal bulge. D) volcanism. E) the crust cooling and shrinking.

Q: Mercury's surface most resembles which of these? A) the Earth's deserts B) the lunar far side C) the lunar mare D) Venus' polar regions E) Mars' deserts

Q: One of the effects of Mercury's very slow spin is A) extreme variations in its surface temperature. B) an intensely powerful magnetic field. C) tectonic activity. D) wind patterns that are slow, but global in size. E) large variations in the size of its polar cap.

Q: Which body has the densest atmosphere? A) Mercury B) Venus C) Earth D) Mars E) our Moon

Q: Why are Mars' seasons more extreme than those of the earth? A) Mars' seas dried up long ago. B) Mars' axial tilt is slightly more than our 23.5 degrees. C) Mars' orbit is more eccentric than our almost circular one. D) Mars' weather is affected by evaporation from the polar ice in its summer. E) All of these contribute to the huge seasonal changes that Mars experiences.

Q: The main constituent of the Martian atmosphere is A) hydrogen. B) helium. C) methane. D) carbon dioxide. E) nitrogen.

Q: What is the main constituent of the atmosphere of Venus? A) oxygen B) nitrogen C) hydrogen D) carbon dioxide E) sulfuric acid

Q: The atmospheric pressure on Venus A) shows an extreme change with the seasons. B) is much lower than on Earth. C) is about the same as on Mercury. D) is much higher than on Earth. E) causes variations in surface temperature.

Q: Mercury presents the same side to the Sun A) every other orbit. B) all the time, just like our Moon. C) every 12 hours. D) every third orbit. E) twice every orbit.

Q: Venus' rotation on its axis A) is the fastest of the terrestrial planets. B) is clockwise, unlike most other solar system objects. C) shows it is tidally locked in its orbit around the Sun. D) is highly tilted to its orbital plane, causing large seasonal changes. E) prevents us from seeing all of its surface features.

Q: How does Mercury's rotation relate to the Sun? A) It always keeps one face tidally locked toward the Sun, as our Moon does with us. B) Its year is much shorter, only 88 days, than its slow rotation of 243 days on its axis. 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.

Q: Which planet shows the widest range of surface temperatures between day and night? A) Mercury B) Venus C) Earth D) Mars E) Uranus

Q: Which three worlds have almost identical densities? A) Mercury, Venus, and Earth B) Mercury, Mars, and our Moon C) Deimos, Phobos, and our Moon D) Earth, Moon, and Mars E) Mercury, Earth, and Mars

Q: Which of these gets so bright as to be seen in daylight at times? A) Mercury B) Venus C) Mars D) Jupiter E) Saturn

Q: Running water played a major role in shaping Mars in ancient times.

Q: Running water continues to be the major erosive factor of Mars today.

Q: Carbon dioxide is the predominant atmospheric gas on Venus.

Q: Mercury's magnetic field is generated by the same dynamo effect as Earth's.

Q: Venus and Mercury both have magnetic fields similar to Earth's.