H yperion is one of the smaller moons of Saturn. It was discovered by William Cranch Bond. It has a pock-marked body and is the largest irregularly shaped satellite 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 moon's rotational period is not constant and varies from one orbit to the next. Hyperion is redder than Phoebe and closely matches the color of the dark material on Iapetus. The largest crater on its surface is approximately 120 kilometers (75 miles) in diameter and 10 kilometers (6.2 miles) deep. The irregular shape of Hyperion and evidence of bombardment by meteors makes it appear to be the oldest surface in the Saturn system.