Brothers in the Night

The Cassini spacecraft captures this dual portrait of an apparently dead moon and one that is very much alive. Tethys, in the foreground, shows no signs of recent geologic activity. Enceladus, instead, is covered in fractures and faults - near its South Pole in particular - and spews icy particles into space from active vents. Tethys' giant crater Odysseus lurks in the dark just west of the terminator. North on the moons is up.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Nov. 29, 2005 at a distance of app.x 970.000 Km (roughly 600.000 miles) from Tethys and at a Sun-Tethys-spacecraft angle of 122°. Cassini was then 1,1 MKM (700.000 miles) from Enceladus. Image scale is about 6 Km per pixel on Tethys (at left) and 7 Km per pixel on Enceladus (at right).