Jupiter and the Galilean Moons

Montage photo of Jupiter and the Galilean moons

Jupiter's Great Red Spot with, from top to bottom: Io, Europa, Ganymede and Callisto


The four Galilean moons, individually.

Montage photo of the Galilean moons showing proportionate sizes

Left to right: Io, Europa, Ganymede and Callisto, showing comparative size.

Io and Earth's Moon, side by side

Io and the Earth's Moon together. Io is slightly larger. This picture is taken from Solarviews.

Images taken by the Galileo and Cassini probes, and are in the public domain. You can find more superb shots of all things astronomical at the Astronomy Picture of the Day website.