A Pitted Space Rock
16 May 2007



Credit: NASA/JPL/Space Science Institute

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

Hyperion (280 km across) is tumbling chaotically in space, with no fixed rotational axis. This is a unique dynamical phenomenon among planetary satellites.

Hyperion's dark surface is pitted with numerous craters. The massive impacts rendered the moon a spongy appearance. Like Saturn's small, innermost moons, the structure of impact-eroded Hyperion is believed to be highly porous.

Hyperion's non-spherical shape and relatively large size led some scientists to speculate that it is a fragment from a larger object that was shattered due to a tremendous, ancient impact.

The image was taken in visible light with Cassini's narrow-angle camera on 12 April 2007, at a distance of approximately 1.1 million km from Hyperion. Scale in the original image was 7 km per pixel. The image was contrast enhanced, and magnified by a factor of two.

Hyperion orbits Saturn every 21.27 days, at an average distance of approximately 1.5 million km.

In Greek mythology, Hyperion was one of the brothers and sisters of Saturn, known as the Titans. It was also the father of Helios (a Sun god), and son of Gaea (Earth) and Uranus (Heaven).

Further Reading

Two Small Moons Align


The Cassini-Huygens Mission


The Eight Planets


Aymen Mohamed Ibrahem

Senior Astronomy Specialist

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