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Phoebe Temperature Maps
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Phoebe Temperature Maps

November 12, 2009
A montage of maps of Saturn's moon Phoebe shows surface temperatures at various times of the day as determined by the composite infrared spectrometer onboard Cassini during the 11 June 2004, Phoebe flyby. The asterisk on each map shows the location of the subsolar point, where the Sun is directly overhead. This point moves across the surface as Phoebe rotates. It is morning in regions to the left of the subsolar point, and afternoon in regions to the right.

The different colors indicate different temperatures. Equatorial temperatures peak in the early afternoon near 112 K, plunging to 78 K before dawn, and are even colder at higher latitudes. The large day/night temperature contrasts imply that Phoebe's surface is covered in loose dust or ice particles that store little heat and thus cool off rapidly at night. Regions of Phoebe's surface that were not observed are shown in black.

Most of the maps show the effect on surface temperatures of the large crater-like depression seen in Cassini's visible-wavelength images of Phoebe, which is located just left of center in these maps. Crater walls that are shadowed and cold in the early morning in the first map are sunlit and warm in the late afternoon in the final map.

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


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