Thursday, 29 November 2012

Pacman found near Saturn

Astronomers have seen that the temperature of Saturn's moon Tethys has hotter regions uncannily like the 1980s arcade game character Pac-Man. A similar feature was spotted in 2010 on Mimas, another Saturnian moon.

A report in Icarus suggests that the effect is due to high-energy electrons bombarding the sides of the moons which face their direction of orbital travel. This compacts the surfaces to a hard, icy texture and does not heat or cool as rapidly as the unaffected surface.

Thermal images of both moons were obtained by the Cassini-Huygens mission, launched in 1997 to study the Saturn system in detail. The temperatures seen by the spacecraft are distinctly chilly - the warmest parts of Tethys were at - 183C, but inside the "mouth" of the Pac-Man shape it was 15C cooler.

At the time of the finding of the first Pac-Man shape on Mimas, scientists were unsure what might be the cause, theorising that differing surface textures probably played a role. The existence of another such shape nearby has cemented the idea that fast-moving electrons are responsible.

"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, of the Southwest Research Institute in Texas and lead author of the study. "The Saturn system - and even the Jupiter system - could turn out to be a veritable arcade of these characters," she said.

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