This was
your sky.

Io and Callisto Mutual Event

Here, two of Jupiter's Galilean moons, Io and Callisto, engage in a mutual event. Io, bright and volcanic, is eclipsed by the darker, cratered Callisto. This sequence was captured from Earth using a small telescope, a challenging observation project. Both moons are larger than Earth's Moon, with Io about 3,640 kilometers across and Callisto 4,820 kilometers.