Cassini encounters a tumbling space rock
27 March 2007


Credit: NASA/JPL/Space Science Institute


NASA recently published an exquisite image of Saturn's enigmatic moon, Hyperion, acquired by the Saturn-bound Cassini spacecraft.


Hyperion (280 km across) is unique among planetary satellites, as it is chaotically tumbling in space, and highly eroded by meteoritic impacts. Its rotational axis wobbles randomly in space. Only minor planet Toutatis is known to rotate chaotically. To an observer on the surface of Hyperion, the Sun will rise from, and set in, unpredictable locations on the horizon.


It is believed that Hyperion's interior is porous, resembling a gigantic pile of rubble.


The image was taken on 15 February 2007, with Cassini's narrow-angle camera, applying an infrared filter. The spacecraft was approximately 224,000 km from Hyperion. Image scale is 1 km per pixel.


Hyperion was discovered in 1848. It orbits Saturn every 3 weeks, at a distance of approximately 1.48 million km. In Greek mythology, Hyperion was a Titan, son of Gaia (Earth) and Uranus (heaven), and father of Helios (the Sun).


Further reading


Three tiny moons align

A banded moon

Aymen Mohamed Ibrahem

Senior Astronomy Specialist

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