June 27, 2006

Rhea, Mimas and Enceladus

This is an interesting animation, taken by the spacecraft Cassini, which is orbiting Saturn. The movie was taken on January 27, 2006, using 59 clear-filter images taken over a period of about 40 minutes. The camera was centered on Rhea, with Mimas passing by on the top and Enceladus on the bottom.

What this animation doesn't show you is the apparent distance between these three moons of Saturn. In the animation, it looks like Rhea, the large moon in the center, orbits between Mimas and Enceladus. In fact, if you look at this diagram, you'll see that Mimas and Enceladus are much closer in to Saturn than Rhea is; i.e., Rhea has an orbit that's much further out from Saturn. However, Rhea is much larger (with a diameter of 1,528.8 km) than either Mimas (396.6 km) or Enceladus (504.2 km).

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