Astronomy Chapter 12 – Flashcards
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What substance is underabundant (compared to Jupiter) in the atmosphere of Saturn?
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Helium
The fraction of helium on Saturn (7.4 percent) is about half the fraction on Jupiter (14 percent).
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Which of the following statements is NOT true about Saturn's moon Titan?
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Its surface temperature is about the same as that of Earth.
This is false. Titan's surface temperature is 94 K, much cooler than Earth's.
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The Roche limit is that distance from a planet where ________.
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tidal forces are equal to internal forces
The Roche limit is the tidal stability limit, the critical distance inside of which the moon is destroyed. Only smaller ring particles are found within the Roche limit; larger bodies would be broken up by tidal stress.
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Saturn's rings are composed of mainly which of the following?
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Water ice
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The surface temperature of Saturn, though cold, is much higher than would be expected from the amount of solar energy it receives. Which of the following factors is thought to be the primary cause of this higher temperature?
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Continued gravitational settling of liquid helium
Because of Saturn's low internal temperature, the liquid helium in its interior condenses to form a continuous helium precipitation that settles toward the planet's core, releasing energy.
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Why is Saturn's atmosphere less varied in color and appearance than Jupiter's atmosphere?
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Saturn's top clouds are thicker, with few holes and gaps, and they obscure the deeper layers.
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Why does the appearance of Saturn's rings change over time as seen from Earth?
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The rings lie in the planet's equatorial plane, which is tilted with respect to the ecliptic.
As Saturn moves along its orbit, the angles at which the rings are illuminated and at which we view them vary.
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If you could find a bathtub big enough for Saturn, the planet would:
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float.
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Saturn's rings are edge-on and vanish when it is at:
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equinox.
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The atmosphere of Saturn is composed mostly of:
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hydrogen and helium.
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Compared to Jupiter, Saturn's atmosphere is:
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more calm with fewer disturbances or storms.
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Saturn's cloud surface appears more uniform than Jupiter's because:
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the cloud layers are thicker, allowing fewer holes to see the colorful layers.
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Why does Saturn have only about half as much helium as a fraction of its total atmospheric composition as do Jupiter, Uranus, and Neptune?
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Helium may have liquefied and precipitated down into the interior of Saturn, reducing the overall proportion of helium in the atmosphere.
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When Voyager 2 was routed to fly by Saturn, it was originally the plan to have the satellite fly through the Cassini gap. Why would this have been a bad idea?
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The gaps in Saturn's ring system (including the Cassini gap) are not actually empty space, rather they are an area of low density in the rings.
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The Roche limit is the point at which:
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the external tidal forces on an object become greater than the internal forces that hold it together.
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Titan is an interesting moon because:
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it has a rich atmosphere that may resemble that of the early Earth.
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The Cassini spacecraft found evidence that the E Ring is related to Enceladus through:
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a continual supply of icy particles spewed via volcanism on Enceladus.
