QQQQ - Saturn system
Explain the source of Saturn's internal heat. As part of your answer, state explicitly how we know that Saturn even has an internal heat source to begin with that is different from and more powerful than Jupiter's internal heat source. Also, explain why this heat source doesn't exist on Jupiter.
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Saturn's system of satellites has taught Astronomers many things about the formation and evolution of bodies in the outer solar system.
a) (8 pts) Name and explain two reasons why Astronomers think that the icy moons closest to Saturn are smaller than the moons furthest from Saturn (feeding zone sizes and condensation temperatures are not believed the be the reasons).
b) (6 pts) Why is Saturn's moon Titan thought to have a thick atmosphere while Jupiter's outermost moon Callisto has an extremely thin atmosphere, even though the size, density and composition of the two moons is nearly identical?
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Explain what causes the Cassini division, the large gap in the rings of Saturn.
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Explain the two-faced appearance of some of Saturn's icy moons
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Describe the evidence that tells us Saturn's rings are composed of trillions of independently orbiting particles rather than a single solid disk of matter. A diagram may help.
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Explain what Saturn’s moon Titan has a thick atmosphere while Neptune’s moon Triton (similar size, composition and density) does not. As part of your answer, explain what physical properties of Triton support your reasoning.
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We know that Saturn’s moon, Titan, has an atmosphere composed largely of methane (CH4) and other similar gases made from various combinations of Carbon and Hydrogen. However, it is clear from the composition of the Sun, Saturn and the other gas giants that the most abundant gases in the solar system during planetary formation were Hydrogen and Helium. Why does Titan’s atmosphere consist of only these strange, relatively uncommon gases instead of Hydrogen and Helium? Explain. (Note that I am not asking how Titan got its atmosphere in the first place).
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The most common isotope of Helium is called Helium-4, and it has 2 protons and 2 neutrons in its nucleus. Suppose there were a stable isotope called Helium-5 (2 protons and 3 neutrons) that is slightly more massive than Helium-4. Measurements of the ratio of Helium-4 to Helium-5 normally find a 1:1 (equal) ratio, and this ratio was present in the solar nebula when the planets initially formed.
a) (4 pts) One of Saturn’s sources of additional energy is “Helium rain” or the differentiation of Helium in its atmosphere, releasing heat. If you were to measure the ratio of Helium-4 to Helium-5 in the atmosphere of Saturn, which would you expect to find more of?
b) (8 pts) Explain your answer to part (a).
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Explain the concept of the Roche limit for a planet, and describe how is it related to the formation of ring systems. A diagram may help for this answer.
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The ring systems of the planets are all thought to be fairly young (ages of less than about 100 million years).
a) (6 pts) Explain what causes the gradual dissipation of the ring systems.
b) (6 pts) Explain why we think the ring systems are all so young.
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Although Saturn’s ring system is the most spectacular in the solar system, we know that it is only temporary. In fact, it is quite possible that in the past Jupiter had an extensive ring system that has since dissipated.
a) (6 pts) Explain what causes ring systems to gradually disappear over the course of a few hundred million years.
b) (6 pts) How do ring systems form around a planet in the first place?
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If Mimas were struck by an asteroid and moved closer to Saturn (but not so close as to be within the Roche limit)...
a) (3 pts) The orbital period of Mimas would (increase, decrease, stay the same). No explanation needed, though you may show any work for partial credit.
b) (5 pts) Would the location of the Cassini Division move (closer to Saturn, further from Saturn, remained unchanged)? Explain your answer.
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Saturn’s moon, Enceladus, is an example of a moon that formed under conditions of extreme cold, so it is almost pure ice, with a density of about 1 gram per cubic centimeter. Another moon in the solar system, called “X”, has 16 times the mass and twice the size of Enceladus.
a) (4 pts) Show mathematically how the density of “X” compares to that of Enceladus.
b) (4 pts) Explain how the formation conditions of “X” must be different from Enceladus.
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Saturn's moon, Mimas, creates a resonance gap in Saturn’s rings, resulting in the famous photographs of the "Cassini Division", a visible gap in the rings of Saturn. Jupiter does the same thing to the asteroid belt, but the only evidence is statistical. In other words, one cannot take a photograph of the “gap” in the asteroid belt (even if the asteroid belt were dense enough to be visible as a unit like Saturn’s rings) because there is no “gap” in space...only a gap in the histogram of periods showing that asteroids tend not to have orbital periods that are simple fractions of Jupiter’s orbital period. Explain why we can see Saturn’s gap but not the gap in the asteroid belt.
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Saturn’s moon Titan shares the same size, mass and composition with Neptune’s moon Triton and Jupiter’s moon Ganymede, yet Titan is the only one of the three bodies with a significant atmosphere.
a) (4 pts) Explain why Titan has an atmosphere while Ganymede does not.
b) (4 pts) Explain why Titan has an atmosphere while Triton does not.