Wednesday, November 23, 2005
Rhea in Sight
The intrepid Cassini probe has a major encounter with the moon Rhea Friday.
It looks rather like our own moon with some white streaks, but don't be fooled: this baby is two-thirds ice. Two Rheas side by side would just approach the lunar diameter--still a pretty big ice cube.
This far out from the sun (880 million miles) ice is frozen so solid that it acts much like rock. On other icy moons we've seen evidence of "geology," namely geysers and volcanoes, faulting and quakes, cliffs and erosion of material, and the like.
Scientists don't expect huge discoveries on Rhea, but they are interested in different cratering patterns which suggest that melted ice from the interior of Rhea once erupted to the surface and wiped out some older craters.
In mythology, Rhea was the consort of Saturn. Saturn had a nasty habit of eating their children, out of fear of being overthrown. Rhea tricked her husband into eating a rock instead of their child Zeus. The baby god grew up, founded the Olympian god-community, and overthrew Saturn and the rest of the Titans. Saturn's moons are mostly named for various Titans and those associated with Saturn. One or two appear in Jupiter orbit, and some of the new Saturn moons have names unfamiliar to me, being as I'm less familiar with Inuit mythology than Mediterranean.
Anyway, with a decent telescope, you can see Rhea and four or five other moons in orbit around Saturn. Titan is fairly easy. On subsequent nights, one can catch the moons in their slow orbits around the planet.
And about that rock-eating episode ... I don't know about the early physical development of Titans, but anyone who can be tricked into eating a rock, for whatever reason, is probably destined to be overthrown in deitydom.
