Using a piece of equipment called an infrared spectrometer, NASA scientists have discovered an unusual quality in two of Saturn’s many moons: the warm and cool areas on their respective surfaces create a pattern that’s a dead ringer for Pac-Man, everyone’s favorite ghost-chomping arcade game character. Researchers discovered the first Pac-Man–that’s their official designation for the phenomenon–on the moon Mimas in 2010, and recently found another on Tethys.
Aside from the obvious cool factor, these discoveries also share worthwhile insight about the nature of the planet and its satellites. And because I’m not an astronomer, I’ll let NASA take it away:
Scientists theorize that the Pac-Man thermal shape on the Saturnian moons occurs because of the way high-energy electrons bombard low latitudes on the side of the moon that faces forward as it orbits around Saturn. The bombardment turns that part of the fluffy surface into hard-packed ice. As a result, the altered surface does not heat as rapidly in the sunshine or cool down as quickly at night as the rest of the surface, similar to how a boardwalk at the beach feels cooler during the day but warmer at night than the nearby sand. Finding another Pac-Man on Tethys confirms that high-energy electrons can dramatically alter the surface of an icy moon. Also, because the altered region on Tethys, unlike on Mimas, is also bombarded by icy particles from Enceladus’ plumes, it implies the surface alteration is occurring more quickly than its recoating by plume particles.
And according to scientist Carly Howett, these moons may not be alone. “Finding a second Pac-Man in the Saturn system tells us that the processes creating these Pac-Men are more widespread than previously thought,” she said. “The Saturn system – and even the Jupiter system – could turn out to be a veritable arcade of these characters.”