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您可以称此为《小精灵续集》（Pac-Man, the Sequel）。美国航空航天局（NASA）负责卡西尼号（Cassini）探测器使命的科学家在土星星系中，发现了又一个形同20世纪80年代《小精灵》系列视频游戏图标的形像——这次是在土星卫星土卫三（Tethys）上（第一个在2010年发现于土卫一[Mimas]）。这个图案是在卡西尼号的合成红外光谱仪获取的热敏数据中显现出来的，温度较高的区域构成小精灵（Pac-Man）的形状。

以上左图为土卫一，右图为土卫三。

《伊卡洛斯》（Icarus）杂志最近在网上发布的一篇论文的主作者卡莉·豪威特（Carly Howett）说“在土星星系中发现第二个小精灵向我们说明，形成这些小精灵的过程比以前认为的更加普遍。”“土星星系——甚至木星星系——其实都可能是有着这些形象的不折不扣的游戏中心。”

科学家推断，土星的卫星上出现小精灵形状的原理是，有高能电子轰击到在轨道上围绕土星运行的卫星前行方向一面的低纬度地区。这种轰击将那些蓬松的表面部分变成了坚冰。其结果是，被改变了的这部分表层与表层其余部分相比，在阳光照耀下升温较慢，夜间冷却也没那么迅速，类似于海滨人行步道相对于它附近的沙滩而言，白天感觉较凉爽，而夜间却比较温暖。在土卫三上再次发现小精灵形状再次确定，高能电子能够给一个冰冷卫星的表层带来极大改变。

设在马里兰州格林贝尔特市（Greenbelt）的美国航空航天局戈达德宇航中心（Goddard Space Flight Center）的光谱仪首席研究员麦克·弗拉萨尔（Mike Flasar）说：“红外线波长方面的研究为我们提供了有关行星和卫星成形过程的大量信息。”

卡西尼-惠更斯（Cassini-Huygens）使命是由美国航空航天局、欧洲航天局（European Space Agency）和意大利航天局（Italian Space Agency）合作进行的一个项目。

Scientists with NASA’s Cassini mission have spotted a second feature shaped like the 1980s video game icon Pac-Man in the Saturn system, this time on the moon Tethys.

You could call this “Pac-Man, the Sequel.” Scientists with NASA’s Cassini mission have spotted a second feature shaped like the 1980s video game icon in the Saturn system, this time on the moon Tethys. (The first was found on Mimas in 2010.) The pattern appears in thermal data obtained by Cassini’s composite infrared spectrometer, with warmer areas making up the Pac-Man shape.

Mimas is on the left in this image, Tethys on the right.

“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, the lead author of a paper recently released online in the journal Icarus. “The Saturn system — and even the Jupiter system — could turn out to be a veritable arcade of these characters.”

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.

“Studies at infrared wavelengths give us a tremendous amount of information about the processes that shape planets and moons,” said Mike Flasar, the spectrometer’s principal investigator at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency.