Jupiter: Io and Great Red Spot Transit

One of the neatest astronomical events to watch is when a Jovian moon moves in front of the planet - this event is called a "transit". If conditions are right, you can see the shadow of the moon work its way across the face of Jupiter. In this image, Io is making the transit, and its shadow falls directly on the Great Red Spot, which is very pale right now.

Color CCD image taken by Dave O'Toole on 9/18/1999 from Lake Orion, Michigan. The telescope used was a Celestron 8" SCT operating at f/20; the CCD camera used was an SBIG ST-237. Post-processing was done with Adobe Photoshop.

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Image © 1999 David J. O'Toole, used with permission.