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Thought Questions

AstronomyThought Questions

Thought Questions


Why do you think the outer planets have such extensive systems of rings and moons, while the inner planets do not?


Ganymede and Callisto were the first icy objects to be studied from a geological point of view. Summarize the main differences between their geology and that of the rocky terrestrial planets.


Compare the properties of the volcanoes on Io with those of terrestrial volcanoes. Give at least two similarities and two differences.


Would you expect to find more impact craters on Io or Callisto? Why?


Why is it unlikely that humans will be traveling to Io? (Hint: Review the information about Jupiter’s magnetosphere in The Giant Planets.)


Why do you suppose the rings of Saturn are made of bright particles, whereas the particles in the rings of Uranus and Neptune are black?


Suppose you miraculously removed all of Saturn’s moons. What would happen to its rings?


We have a lot of good images of the large moons of Jupiter and Saturn from the Galileo and Cassini spacecraft missions (check out NASA’s Planetary Photojournal site, at, to see the variety). Now that the New Horizons mission has gone to Pluto, why don’t we have as many good images of all sides of Pluto and Charon?


In the Star Wars movie Star Wars Episode VI: Return of the Jedi, a key battle takes place on the inhabited “forest moon” Endor, which supposedly orbits around a gas giant planet. From what you have learned about planets and moons of the solar system, why would this be an unusual situation?

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