'Oddball' moon Hyperion This NASA/ESA/ASI Cassini-Huygens image
reveals the odd shape of Saturn's moon Hyperion and an
intriguing variation in brightness across its surface. Hyperion
is one of the smaller moons of Saturn, with a diameter of 266
kilometres, but larger than Phoebe. It has a pock-marked body
and is one of the largest irregularly shaped satellites ever
observed. Hyperion might have had a major collision which blew
part of the moon away. Its eccentric orbit makes it subject to
gravitational forces from Saturn which have set it tumbling out
of control. The largest crater on its surface is approximately
120 kilometres in diameter and 10 kilometres deep. With evidence
of bombardment by meteors, and its irregular shape, Hyperion
appears to be the oldest surface in the Saturnian system. This
image was taken in visible light with the Cassini-Huygens
spacecraft narrow-angle camera on 20 October 2004, at a distance
of about 2.2 million kilometres from Hyperion. The image scale
is 13 kilometres per pixel.