Scientists working on NASA's Cassini mission have spotted a second feature shaped like Pac-Man on one of Saturn's Moon. The pattern appears in thermal data from the moon Tethys, taken using Cassini's composite infrared spectrometer. A similar thermal pattern was spotted on Saturn's moon Mimas back in 2010.
"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 Carly Howett, lead author of a paper about the phenomenon that was recently published in the journal Icarus. "The Saturn system - and even the Jupiter system - could turn out to be a veritable arcade of these characters."
The current hypothesis about the Pac-Men holds that high energy electrons bombard low latitudes on the sides of Mimas and Tethys that face the sun as they orbit Saturn. These electrons turn those sections of the surface into hard-packed ice, causing them to resist heating or cooling more than the rest of the surface. Also, since Tethys is bombarded by icy particles from Enceladus, the thermal pattern suggests to researchers that the surface alteration is occurring more quickly than the particles can re-coat the object's surface. The Pac-Man pattern can actually be seen subtly in visible-light images of Tethys' surface, appearing as a dark lens-shaped region.
"Studies at infrared wavelengths give us a tremendous amount of information about the processes that shape planets and moons," said Mike Flasar, the Cassini spectrometer's principal investigator at NASA's Goddard Space Flight Center. "A result like this underscores just how powerful these observations are."
When the Cassini data was taken, the daytime temperatures inside the "mouth" of the Pac-Man pattern were 29 degrees Fahrenheit cooler than their surroundings. The warmest temperature recorded on Tethys was -300 degrees Fahrenheit.
"Finding a new Pac-Man demonstrates the diversity of processes at work in the Saturn system," said Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory. "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."
(Image courtesy NASA/JPL-Caltech/GSFC/SWRI)