Cassini captures Tethys in all her glory

Saturn's south pole can be seen swathed in clouds and ribbons of gas with the icy moon Tethys below (Image: NASA/JPL/SSI)
In a portrait of perfect composition, Saturn’s moon Tethys has been captured hanging suspended in space just below the planet’s horizon.

This latest image in Saturn’s family album was captured on 18 October at a distance of 3.9 million kilometres from Saturn by the Cassini spacecraft. It clearly shows the Ithaca Chasma, a vast trench about 65 kilometres (40 miles) wide, on the surface of Tethys.

The icy moon - the ninth of Saturn’s 33 daughters - was first discovered by astronomer Giovanni Cassini in 1684 and named after the youngest of three mythological titans. It is thought that the fissure in its surface arose when Tethys was a cooling sphere of liquid; its crust hardened before cracking as the interior solidified.

The pioneering Cassini-Huygens mission blasted off in 1997 and entered orbit around Saturn in June 2004 to begin its four-year tour of the solar system’s “most beautiful planet” and its moons. The probe has snapped many never-before-seen images of Saturn’s signature rings and challenged astronomers’ theories that its largest moon, Titan, has a watery surface.

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