Wikipedia:Picture of the day/February 7, 2006
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Dione is a moon of Saturn discovered by Giovanni Cassini in 1684. It is named after the titan Dione of Greek mythology and is also designated Saturn IV. Dione is composed primarily of water ice, but as the densest of Saturn's moons (aside from Titan, whose density is increased by gravitational compression) it must have a considerable fraction of denser material like silicate rock in its interior. Photo credit: NASA |