土卫二表面的鲜明虎纹

2024年8月25日

Fresh Tiger Stripes on Saturn’s Enceladus
Image Credit: NASA, ESA, JPL, SSI, Cassini Imaging Team

Explanation: Do underground oceans vent through canyons on Saturn’s moon Enceladus? Long features dubbed tiger stripes are known to be spewing ice from the moon’s icy interior into space, creating a cloud of fine ice particles over the moon’s South Pole and creating Saturn‘s mysterious E-ring. Evidence for this has come from the robot Cassini spacecraft that orbited Saturn from 2004 to 2017. Pictured here, a high resolution image of Enceladus is shown from a close flyby. The unusual surface features dubbed tiger stripes are visible in false-color blue. Why Enceladus is active remains a mystery, as the neighboring moon Mimas, approximately the same size, appears quite dead. An analysis of ejected ice grains has yielded evidence that complex organic molecules exist inside Enceladus. These large carbon-rich molecules bolster — but do not prove — that oceans under Enceladus’ surface could contain life.

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土卫二表面的鲜明虎纹
影像提供: NASA, ESA, JPL, SSI, Cassini Imaging Team

说明: 土卫二（Enceladus）的地下海洋，是否透过裂谷向外排气？土卫二昵称为”虎纹”的长条表面结构，证实会朝太空喷发这颗冰冻卫星内部的冰，形成笼罩在南极上空的冰晶云，并造就了土星神秘的E环。支持的证据来自在2004年到2017年间，绕行土星系统的卡西尼号探测船。这幅高解析的土卫二影像，即是在一次近距离飞越时所拍摄，而其中不寻常的表面虎纹结构，是用泛蓝的假色来呈现。不过，为何土卫二会如此活跃，则仍然是个谜，因为附近和土卫二大小相近的土卫一，是个死寂的卫星。经由分析喷出的冰粒，后来更找到了土卫二内部有复杂含碳有机分子的证据。然而，这些富含碳的大分子，支持但无法证明土卫二地下海洋可能有生命。

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