Astronomy Final
Describe four differences between the Jovian planets and the Terrestrial planets. a. The Jovian planets are larger and more massive than Terrestrial planets, have much lower densities, don't have natural satellites, their compositions are dominated by carbon and oxygen, while Terrestrials are more rocky and metallic. b. The Jovian planets are larger but less massive than Terrestrial planets, have much lower densities, have rings and multiple moons, their compositions are dominated by methane and ammonia, while Terrestrials consist of primarily carbon and silicon oxides. c. The Jovian planets are larger and more massive than Terrestrial planets, have much higher densities, have rings and multiple moons, their compositions are dominated by helium and water ice, while Terrestrials consist of primarily carbon and silicon oxides. d. The Jovian planets are larger and more massive than Terrestrial planets, have much lower densities, have rings and multiple moons, their compositions are dominated by hydrogen and other gasses, while Terrestrials are more rocky and metallic.
D
How can a world as small as Titan keep a thick atmosphere? a. Titan is very cold, so molecules such as nitrogen in its atmosphere do not travel fast enough to escape. b. Titan is very geologically active, so the atmosphere is continuously replenished by volcanic emissions. c. Titan is very dense, so it has enough mass and gravity to keep an atmosphere. d. Titan has a powerful magnetic field that holds molecules in the atmosphere and prevents them from escaping.
A
How do astronomers know Jupiter is hot inside? a. Jupiter is glowing in the infrared and emitting 1.7 times as much energy as it receives from the Sun. b. Jupiter is glowing in the infrared and emitting 1.7 times less energy than it receives from the Sun. c. Jupiter is glowing in the ultraviolet and emitting 1.7 times as much energy as it receives from the Sun. d. Jupiter is glowing in the ultraviolet and emitting 1.7 times less energy than it receives from the Sun.
A
How do comets help explain the formation of the planets? a. Comets are understood to be planetesimals from the outer Solar System. Thus, the composition of ices and dust in the nuclei is the same as that of the original outer solar nebula. b. Comets are understood to be planetesimals from the inner Solar System. Thus, the composition of rock and metal in their nuclei is the same as that of the original inner solar nebula. c. Comets are understood to be fragments of ancient planets. Thus, the composition of rock and metal in their nuclei is the same as that of the first planetesimals. d. Comets are relatively young objects; they cannot survive more than about half a million years. Therefore, comets cannot tell anything about the formation of the planets.
A
How were the rotation periods of Uranus and Neptune measured? a. By measuring the motion of very high clouds of methane ice particles and the effects of the planets' magnetic fields. b. By measuring the motion of their moons and the motion of the planets' magnetic fields. c. By measuring their relative motions and the influence of that motion on the planets' magnetic fields. d. By measuring the motion of very high clouds of methane ice particles and the motion of their moons.
A
What evidence do asteroids provide about the nature of the first planetesimals? a. The largest asteroids may be examples of the original planetesimals; they had differentiated, developed molten metal cores, and sometimes lava flows on their surfaces. b. The largest asteroids may be examples of the original planetesimals; they had radioactive decay in their cores and evidence of volcanism in the past. c. The smallest asteroids may be examples of the original planetesimals; they had radioactive decay in their cores and evidence of volcanism in the past. d. The smallest asteroids may be examples of the original planetesimals; they had differentiated, developed molten metal cores, and sometimes lava flows on their surfaces.
A
What ingredients are needed to power a dynamo effect inside a planet? a. A highly conductive liquid metallic interior that is circulated by convection and spun by the rapid rotation of the planet. b. Rapid rotation and more than one moon with short orbital periods that are close to the planet's surface. c. A massive solid iron core with a low density that has a temperature high enough for radioactive decay. d. A liquid iron core with a high density that is covered by a thick layer of liquid metallic hydrogen.
A
What is the difference between the two ice giants, Uranus and Neptune, and the two gas giants, Jupiter and Saturn? Select all that apply. (Review the Celestial Profiles below and consider other chapter information.) a. Gas giants have masses of about 100 Earth masses. Ice giants have masses of about 15 Earth masses. b. Gas giants consist primarily of hydrogen. Ice giants includes a wide layer of methane-ammonia-water ice. c. Gas giants are surrounded by multiple moons and ring systems. Ice giants have a few moons and no rings, like Terrestrial planets. d. Average densities of gas giants are less than 1 gram per cubic centimeter. Ice giants are much denser, with average densities more than 2 grams per cubic centimeter. e. Gas giants are noticeably nonspherical, their oblatenesses are more than 0.06. Ice giants are closer to a spherical shape, with oblatenesses about 0.02.
A, B, & E
Which of the following are evidence of tectonic features on Jovian moons? Select all that apply. a. Young bright surface of ice on Europa with few craters. b. Surface regions that have been flooded by water on Callisto. c. Long cracks and regions where the icy crust of Europa has moved apart. d. Surface of dark ice on Ganymede with many impact craters and low albedo. e. Active volcanoes and high mountains with almost no craters on Io.
A, C, & E
If Venus once had significant amounts of water, where did that water come from? Where did it go? a. Hydrogen from the solar wind reached Venus's surface due to the lack of magnetosphere and combined with free oxygen. Then water was destroyed by ultraviolet radiation, and hydrogen leaked away into space. b. Water vapor was outgassed from the planet's interior during differentiation. Then it was destroyed by ultraviolet radiation from the Sun, and hydrogen leaked away into space. c. Water vapor was outgassed from the planet's interior during differentiation. Then water was destroyed by strong winds and volcanic eruptions. d. Hydrogen from the solar wind reached Venus's surface due to the lack of magnetosphere and combined with free oxygen. Then water was destroyed by strong winds and volcanic eruptions.
B
How would Mars's atmosphere have evolved differently if the planet had been much closer to the Sun, for example, in Venus's orbit? a. Additional solar heating of Mars's surface would have compensated for its lack of size, so it would have outgassed more water, resulting in atmospheric evolution more similar to Earth's. b. The initial atmosphere of Mars would have been denser and hotter at a location closer to the Sun. Later that atmosphere would mostly have leaked to space because of Mars's small size and higher temperatures. The result would likely be similar to the thin atmosphere of Mars that we know today. c. In the area of Venus's orbit, solar ultraviolet radiation causes a runaway greenhouse effect regardless of the planet's size, so the atmosphere of Mars would have been similar to that of Venus today: thick and hot. d. Solar wind and ultraviolet radiation from the Sun would have completely destroyed Mars's atmosphere and made it similar to the Moon and Mercury at that distance.
B
If Venus and Earth outgassed a similar amount of CO2 early in their histories, why are their surface temperatures so different today? a. Venus didn't have a detectable magnetic field, so the solar wind reached Venus's surface and evaporated additional CO2 from the crust, increasing the greenhouse effect and making its surface much hotter. b. Venus was closer to the Sun, water tended to be in the atmosphere rather than in oceans, and CO2 couldn't be dissolved. Therefore, the runaway greenhouse effect made the surface of Venus much hotter. c. Venus didn't contain any water, so CO2 couldn't be dissolved and converted into sediments. Therefore, the runaway greenhouse effect made its surface much hotter. d. Venus's moon fell onto the planet with a catastrophic impact, producing massive ejecta and increasing the abundance CO2 of in the atmosphere. Therefore, the greenhouse effect made its surface much hotter.
B
Look at the figure below showing Uranus and its largest moons. Assuming that Miranda is on the far side of Uranus, what does this image tell you about how the moons formed? a. All of the moons formed far from Uranus and were captured by its gravity. b. All of the moons probably formed with Uranus as it accreted. c. All of the moons, except Miranda, probably formed with Uranus as it accreted; Miranda formed far from Uranus and was captured by its gravity. d. Miranda probably formed with Uranus as it accreted; all other moons formed far from Uranus and were captured by its gravity.
B
Look at the figure below. Compare the visual and UV images of Jupiter. What do you notice? What does it mean? a. Belts and zones are not visible in the UV. This means that Jupiter's own rotation speed is less than the speed of clouds in its atmosphere. b. The auroras do not radiate in the visible but do radiate in the UV. This means that the gases being excited by the magnetic field are very hot. c. The auroras do not radiate in the visible but do radiate in the UV. This means that the gases being excited by the magnetic field are very cold. d. Belts and zones are not visible in the UV. This means that Jupiter's own rotation speed is greater than the speed of clouds in its atmosphere.
B
Name four properties of Mars that are different from those of Earth today. a. No differentiation of the interior; slow rotation; no atmosphere; old cratered surface. b. No magnetic field; lower density; thin atmosphere of mostly CO2; no plate tectonics. c. No differentiation of interior; slow rotation; thin atmosphere of mostly CO2; no plate tectonics. d. No magnetic field; lower density; no atmosphere; old cratered surface.
B
Name four properties of Mars that are similar to those of Earth today. a. Magnetic field; average density; atmospheric chemical composition; active water erosion of the surface. b. Differentiated body; location in the Solar System; has weather and seasons; surface temperatures can be Earthlike. c. Differentiated body; location in the Solar System; atmospheric chemical composition; active water erosion of surface. d. Magnetic field; average density; has weather and seasons; surface temperatures can be Earthlike.
B
Saturn's moons formed in the same way as the Galilean moons formed around Jupiter. True or false? How do you know? a. True. Saturn is very similar to Jupiter in terms of size, mass, composition, and distance to the Sun; hence, their moons formed in the same way. b. False. Saturn was not hot enough during its system's formation to cause the densities of its regular moons to follow the condensation sequence. c. False. All of Saturn's moons were captured from asteroids or Kuiper belts, while the Galilean moons formed together with Jupiter. d. True. All Saturn's regular moons formed together with the planet, have prograde motion and follow the condensation sequence.
B
The image below shows a segment of the surface of Jupiter's moon Callisto. Why are portions of the surface dark? Why are some craters dark and some white? What does this image tell you about the history of Callisto? a. Callisto is a mixture of rock and ice; dark surfaces are rocky and ice-free. Dark craters formed after meteorite impacts and white craters are vents of icy volcanoes. The surface of Callisto is rather old. b. The surface has been modified by the sunlight; also dust particles have accumulated on it. Dark craters are old, while white craters are young and expose fresh white ice. The surface of Callisto is rather old. c. Callisto is a mixture of rock and ice; dark surfaces are rocky and ice-free. Dark craters are old, while white craters are young and expose fresh white ice. Callisto has been geologically active. d. The surface has been modified by sunlight; also dust particles have accumulated on it. Dark craters formed after meteorite impacts and white craters are vents of active volcanoes. Callisto has been geologically active.
B
What are the hypotheses for how the bodies in the Kuiper Belt and the bodies in the Oort Cloud formed? a. The Oort Cloud objects are former bodies of other star systems that were captured by the Sun's gravity. The KBOs formed in the asteroid belt and were ejected later. b. Icy bodies formed in the outer part of the solar nebula and were ejected out from the disk to form the Oort Cloud; others stayed in the disk as the Kuiper Belt. c. Rocky bodies formed in the outer part of the solar nebula and were ejected out from the disk to form the Kuiper Belt; others stayed in the plane of the Solar System as the Oort Cloud. d. The Oort Cloud objects are fragments of the former ninth Solar System planet that was destroyed. The KBOs formed in the asteroid belt and were ejected later.
B
What does the difference in crater distributions on the four Galilean moons tell you about their histories? Answer by using Io and Callisto as examples. a. Jupiter's gravity deflects more meteorites to distant Callisto than to nearest Io. Since Io is heavily cratered but Callisto lacks craters, Io's surface is older and Calisto's is continuously recycled. b. Jupiter's gravity attracts more meteorites to nearest Io than to distant Callisto. Since Callisto is heavily cratered but Io lacks craters, Callisto's surface is older and Io's is continuously recycled. c. Jupiter's magnetic field deflects more meteorites to distant Callisto then to nearest Io. Since Io is heavily cratered but Callisto lacks craters, Io's surface is older and Calisto's is continuously recycled. d. Jupiter's magnetic field attracts more meteorites to nearest Io than to distant Callisto. Since Callisto is heavily cratered but Io lacks craters, Callisto's surface is older and Io's is continuously recycled.
B
What evidence can you point to that Venus does not have plate tectonics? a. Folded mountain ranges are widespread, such as near Lakshmi Planum and Maxwell Montes. The large size of the shield volcanoes shows that Venus's crust is not moving over hot spots. b. Folded mountain ranges occur only in a few places. The large size of the shield volcanoes shows that Venus's crust is not moving over hot spots. c. Folded mountain ranges occur only in a few places. There are no continents on Venus. d. Folded mountain ranges are widespread, such as near Lakshmi Planum and Maxwell Montes. Much of Venus's surface is covered by lava flows.
B
What evidence suggests that meteorites were once part of larger bodies broken up by impacts? a. All meteorites have irregular shapes and came from the asteroid belt where all objects are spherical; this means that asteroids split before their fragments fall on the Earth's surface. b. Crystals in iron meteorites show that they cooled very slowly; this low cooling rate is consistent with existence in bodies much larger than the meteorites' size. Stony and iron meteorites resulted when these bodies melted and differentiated into metal cores at their centers with stone on top, and then were later fragmented. c. The mass and size of typical meteorite falls are much smaller than for average objects in the asteroid belt, therefore asteroids must fragment. d. Many collisions in the asteroid belt are observed each year through Earth-based and orbital telescopes, therefore asteroids are constantly splitting to pieces and may be fragments of a Terrestrial-type planet formed and destroyed at early stages of the Solar System.
B
What is the difference between a meteoroid and an asteroid? Is there a sharp distinction? a. Asteroids are smaller than meteoroids, but there is no sharp distinction in their sizes. b. Meteoroids are smaller than asteroids, but there is no sharp distinction in their sizes. c. A meteoroid is smaller than an asteroid and can be a part of it; an asteroid has a radius larger than 1 km, but a meteoroid is smaller than 1 km. d. An asteroid is smaller than a meteoroid and can be a part of it; a meteoroid has a radius larger than 1 km, but an asteroid is smaller than 1 km.
B
What surface features on Mars today indicate that there was significant water erosion in the past? a. Valley networks and impact craters. b. Outflow channels and valley networks. c. Impact craters and outflow channels. d. Stretches of broken and oxidized rock.
B
What type of asteroid is very dark and gray, and where might it be located? (Hint: Refer to the figure below.) a. S-type asteroid. Inner asteroid belt. b. C-type asteroid. Outer asteroid belt. c. M-type asteroid. Inner asteroid belt. d. S-type asteroid. Outer asteroid belt.
B
Where is the oxygen on Mars today? How do you know? a. It leaked away into space due to the weak gravity, as observed in dissipation of matter ejected by geysers. b. It is locked within chemical compounds as oxides in the soils, as is evident by the reddish color of Mars's surface. c. It is mostly not outgassed from the planet's interior yet, as is evident by the low average density of Mars. d. It is locked within carbon in the atmosphere and polar caps as CO2, as is evident by mathematical modeling of atmospheric evolution.
B
Which planet formation step did the Jovian planets undergo that the Terrestrial planets did not? Why? a. Capture of hydrogen and helium gas. The Terrestrial planets are too close to the Sun to undergo this step. b. Capture of hydrogen and helium gas. The Terrestrial planets are not massive enough to undergo this step. c. Differentiation and formation of a dense core. The Terrestrial planets are not dense enough to have enough interior heat. d. Differentiation and formation of a dense core. The Terrestrial planets are too close to the Sun to have enough interior heat.
B
Why is it possible to acquire Moon rocks by traveling to Antarctica or the Sahara? a. These regions are underpopulated, and most of the fallen meteorites are still not found. b. It is easy to recognize rock meteorites from the Moon there because Earth's native rocks are buried under ice or sand. c. The gravity of Earth causes rock meteorites from the Moon to fall only in these regions. d. More meteorites fall there because of Earth's magnetic field arrangement.
B
Why isn't the crust of Venus broken into mobile plates as Earth's crust is? How do you know? a. The mantle of Venus consists of great amounts of sulfur and fluorine, which makes mantle substances more solid and less plastic. So there are no traces of magma eruptions on Venus. b. Low-density, dryness, and pliability of Venus's crust probably prevented it from breaking into rigid plates. On Venus there are no chains of composite volcanoes that form at plate boundaries. c. Venus's crust is much thicker and denser than Earth's, so that probably prevents the crust from breaking. Moreover, there are no shield volcanoes on Venus. d. Strong winds in the dense atmosphere of Venus sufficiently get rid of the interior heat, so there are no interior currents of matter to drive plate motion. Moreover, there are no shield volcanoes on Venus.
B
Describe evidence of crustal movement (horizontal or vertical) on Venus. Select all that apply. a. Widespread folded mountain ranges. b. Rare folded mountain ranges. c. Fault and deep chasms. d. Coronae. e. Large composite volcanoes.
B, C, &D
Does Mars's surface experience any meteorite impacts today? a. No, Mars's atmosphere is very thick and protects the surface even from large meteorites. b. Yes, we can see a lot of craters on the surface of Mars. c. Sometimes. The atmosphere of Mars protects the surface from micrometeorites, but larger meteorites may occasionally impact the surface. d. Yes, the atmosphere of Mars is very thin and its effect is negligible even for micrometeorites.
C
Does Venus's surface experience meteorite impacts today? How do you know? a. No. Since Venus does not have a magnetic field, it does not attract meteoroids onto its surface. b. Yes. Meteorites fall onto Venus's surface often because of the planet's slow retrograde rotation and absence of moons. c. Not many. Since the atmosphere of Venus is very thick, most meteorites cannot reach the surface of Venus. d. Yes. This is confirmed by Venus's atmospheric composition, especially the abundance of deuterium.
C
How are today's atmospheres of Venus and Mars similar? How are they different? a. Both atmospheres make direct observation of the planets' surfaces impossible due to a massive cloud layer. The atmosphere of Venus contains hydrogen, and the atmosphere of Mars contains oxygen. b. Both atmospheres consist of primarily CO2 and protect the surface from micrometeorite impacts. The atmosphere of Venus additionally contains hydrogen, and the atmosphere of Mars contains oxygen. c. Both atmospheres consist of primarily CO2 and protect the surface from micrometeorite impacts. The atmosphere of Venus is very thick, and Mars's atmosphere is very thin. d. Both atmospheres make direct observation of the planets' surfaces impossible due to a massive cloud layer. The atmosphere of Venus consists of CO2, and the atmosphere of Mars consists of inert gases.
C
How does belt-zone circulation transport energy—by radiation, conduction, or convection? Explain your answer. a. Radiation. Jupiter's magnetic field deflects the solar wind and traps high-energy particles in belts and zones; these particles then transport energy. b. Conduction. Hot particles from Jupiter's center collide with colder particles in upper layers and transport thermal energy. c. Convection. Heat flowing upward from the interior causes rising currents in the bright zones, and cooler gas sinks in the dark belts. d. By none of these methods.
C
Most meteorites were once part of which type of celestial object? a. Terrestrial planets. b. Jovian planets. c. Asteroids. d. Comets.
C
Name four properties of Venus that are similar to those of Earth today. a. Equatorial radius; mass; surface temperature; atmospheric composition. b. Slow rotation; magnetic field; surface temperature; atmospheric composition. c. Equatorial radius; mass; average density; location within the Solar System. d. Retrograde rotation; magnetic field; density; location within the Solar System.
C
The Cassini spacecraft recorded the image below of Saturn's A ring and the Encke Gap. What do you see in this photo that tells you about processes that confine and shape planetary rings? a. There are dark and white lines in the rings. Dark lines are formed by Saturn's magnetic field; white lines are formed by the magnetic field of Titan. b. There is a wide gap and multiple ringlets in the picture. The gap occurred due to Saturn's interaction with Jupiter; the ringlets occurred due to its interaction with moons. c. There is a wide gap and multiple ringlets in the picture. The gap is shaped by resonance with satellites outside the rings; the ringlets are caused by shepherd satellites. d. There are dark and white lines in the rings. White lines are formed from ice particles of Saturn's moons; dark lines are formed from rocky particles of Saturn.
C
What are Kirkwood gaps and what causes them? a. Certain orbits in the asteroid belt that are almost free of asteroids. The gaps are caused by Jupiter's magnetic field lines. b. Certain orbits in the asteroid belt that contain especially many asteroids. The gaps are caused by Jupiter's magnetic field lines. c. Certain orbits in the asteroid belt that are almost free of asteroids. The gaps are caused by orbit resonance with Jupiter. d. Certain orbits in the asteroid belt that contain especially many asteroids. The gaps are caused by orbit resonance with Jupiter.
C
What is the difference between a comet's dust tail and a comet's gas tail? a. A dust tail is curved, uniform, and consists of charged particles carried away by the solar wind. A gas tail contains neutral gases blown outward by the pressure of sunlight and directed straight outwards from the Sun. b. A dust tail contains charged particles carried away by the solar wind, which are directed straight outwards from the Sun. A gas tail consists of neutral particles blown outward by the pressure of sunlight and may be curved because of gravitational perturbations. c. A gas tail is ionized gas carried away by the solar wind and may show effects of the local magnetic field. A dust tail is composed of solid debris blown outward by the pressure of sunlight and may be curved because dust particles follow individual orbits. d. A gas tail is curved, uniform, and consists of ionized gas carried away by the solar wind. A dust tail is blown outward by the pressure of sunlight and is always directed straight outwards from the Sun.
C
What observational properties of Uranus's rings show that small moons must orbit among the rings? a. The rings of Uranus are stable, wide, and evenly distributed; therefore, there can be only small moons among the rings. Large ones would destroy the ring system. b. The rings of Uranus are stable, wide, and evenly distributed; therefore, there should be shepherd satellites to keep the material confined to the ring. c. The rings of Uranus are stable, narrow, and have defined edges; therefore, there should be shepherd satellites to keep the material confined to the ring. d. The rings of Uranus are stable and have defined edges; therefore, there can be only small moons among the rings. Large ones would destroy the ring system.
C
Why are belts and zones wrapped entirely around Jupiter? a. Heat flows upward and forms zones, cooler gas sinks in belts, and the planet's slow rotation does not destroy this pattern. b. The planet has a large temperature difference between the poles and equator. Cold gas forms belts near the poles, hot gas forms zones near the equator. c. The planet's rapid rotation stretches the high- and low-pressure areas into belts and zones that circle the planet. d. The planet has a strong magnetic field that drives the gas particles in the planet's upper atmosphere and stretches layers into belts and zones.
C
Why do the belts and zones on Saturn look so much fainter than the ones on Jupiter? a. Clouds on Saturn have different chemical compositions than those on Jupiter. Saturn's clouds absorb much more light than they reflect and emit. b. Unlike on Jupiter, belts and zones on Saturn have similar chemical composition. That's why they are difficult to distinguish. c. Saturn is much colder and the cloud layers where belts and zones form are deeper in the atmosphere. d. Saturn is much hotter but the cloud layers where belts and zones form are cold and they sink deep into the atmosphere.
C
Why doesn't Earth have large volcanoes like those on Mars? a. Earth is not as geologically active as Mars. b. Large mountains on Earth are quickly eroded by the active dense atmosphere. c. Earth's crust is not thick enough to support such large mountains, moreover, its plates move. d. Earth's gravitational field is very strong and it pulls the planet into a spherical shape.
C
Why is Earth considered a planet and not a dwarf planet? a. It is geologically active and has an atmosphere. b. It is spherical and has a moon. c. It is large enough to clear out smaller objects near its orbit. d. Its radius is more than 1500 km.
C
Why isn't Earth's atmosphere as thick as Venus's? a. Earth's thick atmosphere mostly leaked away into space during the large impact when the Moon was formed. b. Earth was cool enough to outgas much less carbon dioxide and more water vapor at the stage of planet differentiation. c. Earth was cool enough to form large liquid water oceans that allowed much of the carbon dioxide to be dissolved from the atmosphere. d. Earth's volcanism is much weaker because of plate tectonics, and volcanoes are the main source of carbon dioxide in the atmosphere.
C
Why isn't the crust of Mars broken into mobile plates as Earth's crust is? a. Mars has a nondifferentiated interior; therefore, it has no tectonic activity. b. The crust of Mars is composed of very solid and heavy metals and is not easy to break. c. The crust of Mars is very thick (since it can sustain large shield volcanoes), too thick to have broken into moving plates. d. Mars has no overall magnetic field, which could break its crust into mobile plates.
C
hy was Pluto reclassified as a dwarf planet? a. The definition of a planet was clarified: a planet must have a spherical shape. Pluto is not large enough to assume a spherical shape. b. The definition of a planet was clarified: a planet must have radius more than 1500 km. Pluto is not large enough and is a dwarf planet. c. The definition of a planet was clarified: a planet must be able to clear away objects orbiting nearby. Pluto is not large enough for this. d. The definition of a planet was clarified: a planet must have radius more than 1500 km. Pluto satisfied this condition when it was discovered, but it has become smaller over time.
C
How are conditions in Uranus's interior determined? a. It is impossible to know about the interior of such a distant object. Mathematical models can be built by complicated computer modeling, but the result is just a hypothesis. b. The mass and radius of Uranus can be measured based on observation of its moons' motion, then their densities are calculated. Then scientists look for the materials on Earth that have exactly the same density as Uranus. c. There were several spacecraft that were able to collect samples of Uranian material from all its layers, and then mathematical models of Uranus's interior were built. d. The mass and radius can be measured based on observation, then the density is calculated. Based on the density and atmospheric spectra, mathematical models of Uranus's interior are built.
D
How do astronomers know that Jupiter has a low density? a. By measuring Jupiter's mass (from orbital data) and radius (direct measurement via spacecraft). Mass divided by volume gives an average density of about 3.1 g/cm^3. b. By measuring Jupiter's radius (from its distance and angular diameter) and orbital speed (from orbital data). Jupiter's size and speed show that it has low density, about 3.1 g/cm^3. c. By measuring Jupiter's radius (from its distance and angular diameter) and rotation speed (observing the Great Red Spot). Jupiter's size and rapid rotation rate yield a density of about 3.1 g/cm^3. d. By measuring Jupiter's mass (from orbital data) and radius (from its distance and angular diameter). Mass divided by volume gives an average density of about 3.1 g/cm^3.
D
Look at the images of Comet Mrkos below. Is the comet shown on its way in around the Sun, on its way out, or is it not possible to tell? a. The comet is on the way out. b. It depends on the composition of the comet nucleus. c. The comet is on the way in. d. It is not possible to tell.
D
Meteors in showers were once part of which type of celestial object? a. Terrestrial planets. b. Asteroids. c. Jovian planets. d. Comets.
D
Name four properties of Venus that are different from those of Earth today. a. Low-density crust and mantle; very strong magnetic fields producing flares; much cooler surface; complete cover by ice and water. b. Very slow, retrograde rotation; no magnetic field; much cooler surface; complete cover by ice and water. c. Low-density crust and mantle; very strong magnetic fields producing flares; very dense and hot atmosphere of mostly CO2; no surface water. d. Very slow, retrograde rotation; no magnetic field; very dense and hot atmosphere of mostly CO2; no surface water.
D
Refer to the table below. Why do meteor showers occur at the same time each year? a. Meteor showers occur when Earth's atmosphere has a certain temperature which depends on the sunlight angle of incidence and, therefore, on the season. b. Meteor showers occur when Earth passes through debris in its orbit that previously was part of the Moon; Earth crosses this debris at the same time each year. c. Meteor showers are associated with Mars and occur when Earth and Mars have a certain mutual arrangement, which repeats at the same time each year. d. Meteors from showers are associated with comets and are orbiting the Sun along their paths; Earth passes through the comet's orbit at the same time each year.
D
The ring systems around Jupiter and Saturn lie outside those planet's respective Roche limits. True or false? How do you know? a. False. No object can lie outside a planet's Roche limit because such an object would quickly escape the planet's gravity and orbit around the Sun. b. True. Jupiter and Saturn are very large and the radius of their Roche limits is smaller than the radius of the planet. c. True. No object can orbit inside a planet's Roche limit because such an object would be quickly dragged into the planet's atmosphere. d. False. If they were located outside the Roche limit, they could hold themselves together as larger objects rather than small dust particles.
D
What do Widmanstatten patterns indicate about the history of iron meteorites? a. They formed in the inner part of the Solar System where the temperature was high enough to melt iron. b. They formed outside the Solar System and were captured just about 100,000 years ago. c. They formed in the cooling interiors of large objects, such as the Jovian planets. d. They formed in the cooling interiors of planetesimal-size objects, smaller than planets.
D
What produces Io's internal heat? a. Radioactive decay in the core. b. Friction due to its geological activity. c. It is heated by Jupiter's high temperature. d. Friction due to tidal interaction with Jupiter.
D
Why didn't ancient astronomers know of Uranus's existence? a. Uranus was much farther away from Earth at that time. b. Uranus had very low brightness at that time because of effects in its atmosphere. c. Uranus surface was much darker at that time. d. Uranus moves very slowly and is relatively faint.
D
Why do astronomers refer to carbonaceous chondrites as unmodified or "primitive" material? a. They formed outside the solar nebula and did not go through complicated processes in the inner part of the early Solar System. b. By studying their structure and composition, it is easy to detect what part of the Solar System they have come from and what age they are. c. They do not have complicated structure and composition and usually contain only one chemical element. d. They contain volatiles and have never been heated, therefore, they conserved the material of the early Solar System.
D