The Cassini spacecraft has been in orbit around Saturn for the better part of a decade, dropping probes into other worlds, finding extraterrestrial methane lakes and dunes made of hydrocarbon sand, documenting storms bigger than Earth - and, in 2010, finding out that Saturn's moon Mimas has a heat-signature that looks like the spitting image of Pac-Man.
Now, Cassini scientists have found a second one, as you can see above, meaning that both Mimas and Tethys are in orbit around Saturn like some sort of celestial Pac-Man arcade game in Predator heat-vision. But seriously, the presence of two planets with such a strikingly similar, and strikingly unique, heat signature is proof that the effect seen on Mimas is no fluke, but that something more systematic is going on around Saturn. Scientists postulate that both moons are being regularly bombarded by high-energy electrons in select areas, decreasing the ability of those areas to absorb heat from the sun. Therefore, when viewed with Cassini's infrared spectrometer, those areas appear darker and lead to the effect shown above.
FYI, Tethys is named after the eponymous Titan and alleged mother of the ancient world's rivers, and whose real-world history may be related (in the way that many Indo-European gods are related) to the Babylonian primordial goddess and embodiment of chaos, Tiamat; and Mimas, which rather famously looks like the Death Star (thanks to that prominent, Australia-sized crater), is named after the serpent-legged giant son of the Greek creation goddess Gaia.
And with the trifecta of video games, space, and mythology completed, my Saturday can officially end.