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原文:
Why does this moon look like a sponge? To better investigate, NASA and ESA sent the Saturn-orbiting robotic spacecraft Cassini zooming past Saturn’s moon Hyperion, once again, earlier this week. One of the images beamed back to Earth is featured above, raw and unprocessed. Visible, as expected, are many unusually shaped craters with an unusual dark material at the bottom. Although Hyperion spans about 250 kilometers, its small gravitational tug on Cassini indicates that it is mostly empty space and so has very low surface gravity. Therefore, the odd shapes of many of Hyperion’s craters are thought to result from impacts that primarily compress and eject surface material — instead of the more typical round craters that appear after a circular shock wave that explosively redistributes surface material. Cassini is on track for another flyby of Saturn’s Dione in about two weeks. Retrospective: All Previous June 3 APODs
中文翻譯:
🌌✨ 為何這顆衛星看起來像海綿？為了更深入調查，NASA和ESA在本週再次派遣環土行星探索器Cassini飛掠土星的衛星Hyperion。上面的圖片是回傳到地球的原始未處理照片。可見到許多不尋常形狀的隕石坑，底部則有不尋常的黑暗物質。
Hyperion直徑約有250公里，但它對Cassini的重力影響小，這顯示它主要是空心的，表面重力極低。因此，許多Hyperion隕石坑的奇特形狀被認為是由於撞擊主要壓縮並噴出表面物質，而不是像典型的圓形隕石坑那樣，在圓形衝擊波的作用下爆炸性地重新分配表面物質。
Cassini將在約兩週後再次飛掠土星的Dione。
#Hyperion #Cassini #NASA #ESA #土星 #宇宙探索 #太空科學 #隕石坑 #海綿衛星 #太空任務 #DioneFlyby #天文學分享
來源:NASA每日圖片
