The Map of Dione

This cylindrical projection global map is one of six new color maps of Saturn's midsized
icy moons, constructed using 10 years of image data from the Cassini spacecraft. Discovered
by Cassini (the astronomer) in 1684, Dione is about 1,120 kilometers across. Based on data
extending from infrared to ultraviolet, the full resolution of this latest space-age map is
250 meters per pixel. The remarkable brightness difference between the tidally locked moon's
lighter leading hemisphere (right) and darker trailing hemisphere clearly stands out. Like other
Saturn moons orbiting within the broad E-ring, Dione's leading hemisphere is kept shiny as it
picks up a coating of the faint ring's icy material. The E-ring material is constantly replenished
by geysers on moon Enceladus' south pole. Lighter, younger surface fractures also appear to cross
the dark, cratered trailing hemisphere.