Jupiter Goes Solo

Jupiter is famous for its four bright Galilean Moons. These are visible through any amateur telescope. You can watch them move and change positions over the course of a few hours with even a modest telescope (such as the Galileoscope, hint, hint).

You don't always see all four Moons, however. Sometimes they pass in front Jupiter or behind it. It's fairly common for Jupiter to have three or even two visible Moons. A few times each century, however, all of the Moons either pass in front of Jupiter or behind it at the same time. Tonight is one of those times. From 12:43am EDT to 2:29am EDT (a more civilized 9:43pm PDT to 11:29 PDT) all four of Jupiter's Moons will be gone leaving a strangely naked planet. I have been observing Jupiter for decades and never seen this (I have seen it with only one Moon which was strange enough). You can check out an animation of what you will see with a telescope tonight or use Sky and Telescope's Jupiter's Moon's Utility to find out what you will see at any given moment.

Unfortunately, it looks to be cloudy here in Tucson tonight. My telescope is sitting at home on the tripod ready to go outside a moment's notice should we get abreak in the clouds. I hope others have clear skies for this rare event.

Reprinted with permission from the Half-Astrophysicist Blog.