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Moon in the night
20 April 2007
Saturn moons Enceladus and Tethys in the night
Enceladus (505 kilometres across) and Tethys (1,071 kilometres across) appear close together in the sky in this image, but in reality, Tethys was more than 260,000 kilometres farther from the Cassini spacecraft - greater than half the distance from Earth to the Moon. Enceladus is easy to identify by the brilliant plume of ice erupting from its south pole.
Although this perspective views the night sides of both moons, the Sun is not the only source of illumination in the Saturn system. Tethys is at a fuller phase with respect to Saturn, and thus its "night side" is more fully lit than that of Enceladus.
The view was acquired from a Sun-Enceladus-spacecraft, or phase, angle of 163 degrees, a viewing geometry in which the microscopic ice particles in its plume brighten substantially.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on 6 June 2006 at a distance of approximately 3.9 million kilometres from Enceladus and 4.2 million kilometres from Tethys. Image scale is 23 kilometres per pixel on Enceladus and 25 kilometres on Tethys.