杏吧原创

A VAST impact scar may lurk on the otherwise fresh face of Saturn鈥檚 moon Titan. It would be the largest such structure on the icy body, which hosts a paucity of craters compared with other moons.

Robert Brown of the University of Arizona in Tucson and colleagues spotted the roughly circular, 1800-kilometre-wide bright patch near Titan鈥檚 equator in infrared images snapped by the Cassini spacecraft. Radar data suggest Titan鈥檚 crust is fractured in this area, as would be expected following an impact. The team conclude that a 60-kilometre impactor slammed into Titan early in its history, creating the patch .

That would be consistent with a that identified possible deposits left by watery flows at the southern edge of the patch: cracks left by the impact may have allowed water to erupt from Titan鈥檚 interior.

Unlike fresh craters, the interior of the patch is only slightly lower than the landscape. 鈥淚t鈥檚 like the ghost of a crater,鈥� says Brown, part of the Cassini team. Charles Wood of Wheeling Jesuit University in West Virginia, also a Cassini team member, doesn鈥檛 buy it. He says the patch could just be a chance alignment of other features.