What`s up with Iapetus?
Monday, June 13, 2011 - 09:00
in Astronomy & Space
Although Saturn's moon Iapetus was first discovered in 1671 by Giovanni Cassini, its behavior was extremely odd. Cassini was able to regularly find the moon when it was to the west of Saturn, but when he waited for it to swing around to Saturns east side, it seemed to vanish. It wasnt until 1705 that Cassini finally observed Iapetus on the eastern side, but it took a better telescope because the side Iapetus presented when to the east was a full two magnitudes darker. Cassini surmised that this was due to a light hemisphere, presented when Iapetus was to the west, and a dark one, visible when it was to the east due to tidal locking.