Extraordinary feature found on Saturn's moon Iapetus

January 9, 2005

The Cassini space probe, currently in orbit around the planet Saturn, has returned extraordinary pictures from the Saturnian satellite Iapetus.

It has long been known to astronomers that Iapetus's surface is divided into two hemispheres, one dark, one light. Now a narrow ridge of massive proportions, 20 km high and 1,300 km long, has been found around the equator of the moon. The height rivals Olympus Mons on Mars-- but Mars is five times bigger than Iapetus.

The origin of this feature is currently unknown. Cassini will next fly by Iapetus in September 2007. The images returned from that pass will have over 100 times greater resolution than the current ones, and scientists hope they will help unravel the mystery.

Iapetus, Saturn's third largest moon, has a diameter of about 1,436 km (892 miles). Jean-Dominque Cassini discovered the moon in 1672; it was also Cassini who determined the color difference on Iapetus.

The Cassini-Huygens mission, named after Giovanni Domenico Cassini (Jean-Dominque Cassini), is a collaborative project with the European Space Agency, the Italian Space Agency, and NASA.