NASA Cassini scientists have found a second 'Pac-Man' moon orbiting Saturn, around the moon Tethys — reported The Register. The first 'Pac Man' discovery was made in 2010, when the team found that a thermal imaging of the icy moon Mimas looked just like the shape of "a Pac Man eating a dot."
"Finding a second Pac-Man in the Saturn system tells us that the processes creating these Pac-Men are more widespread than previously thought," said team member Carly Howett — according to TG Daily. "The Saturn system — and even the Jupiter system — could turn out to be a veritable arcade of these characters," he added.
The explanation for the Pac Man-like shape, according to the scientists, is as follows:
"[...] High-energy electrons bombard low latitudes on the side of the moon that's facing forward as it orbits around Saturn, turning that part of the fluffy surface into hard-packed ice. As a result, the surface doesn't heat as rapidly in the sunshine or cool down as quickly at night as the rest of the surface."
The new images, taken in September2011, show daytime temperatures inside the "mouth" of Pac-Man to be cooler than their surroundings. Mike Flasar, the spectrometer's principal investigator, said, "studies at infrared wavelengths give us a tremendous amount of information about the processes that shape planets and moons." He added, "a result like this underscores just how powerful these observations are," according to TG Daily.
Unlike at Mimas, at Tethys the Pac-Man pattern can also be seen — albeit subtly — in visible-light images of the surface (as a dark lens-shaped region). NASA first noticed this brightness variation in 1980.
Linda Spilker, a Cassini project scientist at NASA's Jet Propulsion Laboratory, said, "finding a new Pac-Man demonstrates the diversity of processes at work in the Saturn system." She added, "future Cassini observations may reveal other new phenomena that will surprise us and help us better understand the evolution of moons in the Saturn system and beyond," according to The Register.