Well this animation has been a long time coming. Back on the 5th July 2009, Ganymede and Callisto had a close approach – no occultation unfortunately, but it was still great to see them so close together.

Ganymede, at 5,200km diameter (1.7 arcseconds) and Callisto at 4,800 km diameter (1.6 arcseconds) are both over 635 million km away. The seeing was only just above average, but both moons show consistent albedo features throughout many frames of the animation.

Click the image below to view the 15 frame animation which covers just over 2 hours of elapsed time.

Ganymede and Callisto Close Approach Animation. Click to Play.

Please read on to find out more about the capture and processing.

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