Moon/shadow transits of Jupiter last Thursday

by Steven Gottlieb

When I was observing at the Sierra Buttes last Thursday at a public star party and last night of the SF State astronomy class, there was a great shadow transit of Io (along the NEB) early in the evening. At the same time, there was a transit of Callisto (further north but initially at a similar longitude) and both the shadow of Io and Callisto were both prominent. In fact, I assumed I was watching the shadow of Callisto since it was so dark and sharply defined (several people found Callisto more obvious than Io's shadow), but I realized the next day using StarryNight Pro that Callisto's shadow transit did not begin until after Jupiter had set. In general, when I've observed satellite transits they often get lost by the time they transit Jupiter's meridian, so I'm not sure what to make of the observation of Callisto?

Posted on sf-bay-tac Jul 26, 2004 22:27:20 PT
Converted by report.pm 1.2 Jan 04, 2005 22:51:43 PT