Hyperion the Sponge Moon

A couple of days ago, the still-active Cassini spacecraft orbiting around Saturn performed a flyby of the small Moon Hyperion, taking high resolution photos of the surface, and showing the sponge-like surface of the moon in a different light. Hyperion is a moderate 250 kilometers wide, yet it doesn’t tug very hard on Cassini.  Performing measurements of its surface gravity, Cassini has shown that the moon is mostly empty space, similar to a pumice stone on Earth.  The odd shapes of the craters are thought to be a result of this.  When an impactor hits Hyperion, it blows the material...

Ceres Like the Moon, Mercury

It’s coming up fast.  The March 6th orbital injection of the Dawn spacecraft about the dwarf planet Ceres is set to be an incredible event.  The latest photos show a much more detailed Ceres that we have seen previously.   The newest images reveal that Ceres is a rocky, cratered world, not unlike the Moon or Mercury.  Still, we have yet to determine the origins of the bright spots on the surface. Just over two weeks from now the world will see an unmasked Ceres.