Io experiences tidal heating primarily because __________.
From Part A, Io's elliptical orbit is necessary to its tidal heating. This elliptical orbit, in turn, is a result of the orbital resonance among Io, Europa, and Ganymede. This orbital resonance causes Io to have a more elliptical orbit than it would otherwise, because __________.
We cannot see tidal forces or tidal heating; rather, we predict that they must occur based on the orbital characteristics of the moons. What observational evidence confirms that tidal heating is important on Io?
The orbital resonance also gives Europa an elliptical orbit, so it also experiences tidal heating. However, Europa experiences less tidal heating than Io, because Europa __________ than Io.
We now know of many Jupiter-size planets around other stars. Suppose that future observations show that one of these planets has two orbiting moons. What additional information, if any, would we need to decide whether these moons experience tidal heating?
--- PROBLEM 2 ---
Listed following are some of the distinguishing geological characteristics of the moons orbiting Jupiter. Match each characteristic to the appropriate moon.
Io: heavily cratered terrain adjacent to much younger terrain; volcanoes currently erupting; hot, glowing lava visible in some photos
Europa: surface features provide evidence of a subsurface liquid ocean; ice covered surface with few impact craters
Ganymede: source of ionized gas in the donut-shaped charged particle belt around Jupiter; largest moon in the solar system