The 400th Anniversary of the discovery of the Galilean moons of Jupiter

In honor of the 400th anniversary of the discovery of the Galilean moons of Jupiter (from largest to smallest - Ganymede, Callisto, Io, Europa), here they are to scale from NASA's Galileo spacecraft (with the exception of a tiny bit of Voyager-derived gap-fill for Callisto).

Processed Images Copyright Ted Stryk, Raw Data Courtesy NASA/JPL