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Anomalous temperatures on Mimas

Anomalous temperatures on Mimas
Anomalous temperatures on Mimas This map illustrates the unexpected and bizarre pattern of daytime temperatures found on Saturn's small inner moon Mimas (396 kilometers in diameter). The data were obtained by the composite infrared spectrometer (CIRS) on Cassini during the spacecraft's closest-ever flyby of Mimas on February 13, 2010. The upper left image shows the expected distribution of temperatures. The white sun symbol shows the point where the sun is directly overhead, which is at midday close to the equator. Just as on Earth, the highest temperatures were expected to occur after midday, in the early afternoon. The upper right image shows the completely different pattern that Cassini actually saw. Instead of the expected smoothly varying temperatures, this side of Mimas is divided into a warm part (on the left) and a cold part (on the right) with a sharp, v-shaped boundary between them. The warm part has typical temperatures near 92 Kelvin (minus 294 Fahrenheit), while typical temperatures on the cold part are about 77 Kelvin (minus 320 Fahrenheit). The lower two panels in the annotated version compare the temperature map to Mimas' appearance in ordinary visible light at the time of the observations. NASA / JPL-Caltech / GSFC / SWRI / SSI