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Dark-stained Iapetus
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Dark-stained Iapetus

November 16, 2009
This near-true colour view from Cassini reveals the colourful and intriguing surface of Iapetus. The images taken with different spectral filters and used for this composite were taken at the same time as the clear frames used in the above composite view of Iapetus' surface. The use of colour on Iapetus is particularly helpful for discriminating between shadows (which appear black) and the intrinsically dark terrain (which appears brownish).

This image shows the northern part of the dark Cassini Regio and the transition zone to a brighter surface at high northern latitudes. Within the transition zone, the surface is stained by roughly north-south trending wispy streaks of dark material. The absence of an atmosphere on Iapetus means that the material was deposited by some means other than precipitation, such as ballistic placement from impacts occurring elsewhere on Iapetus, or was captured from elsewhere in the Saturn system. Iapetus's north pole is not visible here, nor is any part of the bright trailing hemisphere.

Images taken with infrared (centred at 930 nanometres), green (568 nanometres), and ultraviolet light (338 nanometres) filters were combined to create this image. The view was obtained with the Cassini spacecraft narrow angle camera on 31 December 2004, at a distance of about 172 900 kilometres from Iapetus. Resolution achieved in the original image was 1 kilometre per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency.


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