Mimas is a small moon that orbits Saturn and looks much like the Death Star from Star Wars. The Herschel impact crater, which is named after the discoverer of the moon and also which gives Mimas its distinctive look, is 130 kilometers across, with walls that are 5 kilometers high.
Cassini recently took a look at the temperatures on the moon and found that they differed from what was expected. If you click on the image to the right, you will see what the expected temperatures were. Where the sun is shining on Mimas is marked by a white star. Instead, Cassini found a completely different temperature profile. Mimas has warm temperatures near 92 Kelvin (minus 294 Fahrenheit), while the colder temperatures are about 77 Kelvin (minus 320 Fahrenheit).
This figure illustrates the unexpected and bizarre pattern of daytime temperatures found on Saturn’s small inner moon Mimas (396 kilometers, or 246 miles, in diameter). The data were obtained by the composite infrared spectrometer (CIRS) on NASA’s Cassini spacecraft during the spacecraft’s closest-ever look at Mimas on Feb. 13, 2010.
Maybe the light is not from the sun, but rather from the rings and the heat signature is from the planet?