Saturn’s icy moon, Mimas, has long been remarked for its large Herschel Crater giving it the appearance of the Death Star, the fictional space station of Star Wars fame.
Death-Star-esque Mimas, imaged by Cassini — Click for high-resolution view
Perhaps Mimas inspired George Lucas when creating the Death Star? Nope; Voyager was the first to give us close-up views of Mimas, a few years after ‘A New Hope’ was in theatres.
But earlier this year, Mimas revealed another uncanny secret resemblance to something out of recent pop-culture history: Pac-Man!
Mimas Temperature Map – Click for a Pac-tastic Larger Version
So what we’re seeing here is a map of temperature differences placed over a visual-light image of Mimas. If you think it’s curious that the highest temperatures seem to vary in such a way, you’re not alone:
“Even though we can’t explain the observed pattern of surface temperatures on Mimas, the giant Herschel crater is a leading suspect[.]” “The energy of impact that created it several billion years ago has been estimated to be one-seventh of Mimas’s own gravitational energy. Anything much larger would likely have torn the moon apart. We really would like to see if there is also an anomalous temperature pattern on the other side of Herschel, which has not been observed so closely.” – Dr. Mike Flasar, composite infrared spectrometer principal investigator from NASA Goddard Space Flight Center.
The following image gives an idea of how what’s actually occurring on Mimas compared to what would previously be expected:
Comparison between expected temperature-map, actual temperature-map, visual light, and actual temperature-map layered on visual light images. – Click for full version.
A leading theory is that different textures of surface materials (mostly water ice with small amounts of rock) are holding on to heat from the Sun differently, but what is still not understood is why such sharp boundaries exist between these textures — giving the Pac-Man shape. It’s possible that the impact that caused the Herschel Crater distributed the more heat-absorbent materials in that pattern, but Mimas is constantly bombarded by impacts (as can be clearly seen when viewing the high resolution image of Mimas above), which you’d expect to destroy long ago any non-uniform surface make-up.
So for now, no definite answer is available. Luckily, we have the amazing Cassini orbiter up there, collecting more data for the scientists to work with.