天鹅，阿特拉斯和火星
(原标题: A SWAN, an ATLAS, and Mars)
2025-09-26
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彗星C/2025 R2 （SWAN）是内太阳系的新访客，在9月21日拍摄的这张近7度宽的望远镜视野中，它的长离子尾呈对角线延伸。另一颗较暗的彗星C/2025 K1 （ATLAS）也首次进入太阳系内部，可以在天鹅绿色彗发的上方和左侧看到，正好可以在室女座的恒星海洋背景下看到。这两颗新彗星都是在2025年才被发现的，在这个天体框架中，与红色的火星（下图）相连，火星是地球夜空中更熟悉的流浪者。这两颗彗星看起来像是在赛跑，在穿越内太阳系和绕太阳飞行的过程中几乎不分上下。但这颗天鹅彗星已经在9月12日到达近日点或最接近太阳的地方，现在正沿着它的轨道离开。这颗彗星ATLAS仍在返回地球，并将于10月8日通过近日点。
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A new visitor to the inner Solar System, comet C/2025 R2 (SWAN) sports a long ion tail extending diagonally across this almost 7 degree wide telescopic field of view recorded on September 21. A fainter fellow comet also making its inner Solar System debut, C/2025 K1 (ATLAS), can be spotted above and left of SWAN's greenish coma, just visible against the background sea of stars in the constellation Virgo. Both new comets were only discovered in 2025 and are joined in this celestial frame by ruddy planet Mars (bottom), a more familiar wanderer in planet Earth's night skies. The comets may appear to be in a race, nearly neck and neck in their voyage through the inner Solar System and around the Sun. But this comet SWAN has already reached its perihelion or closest approach to the Sun on September 12 and is now outbound along its orbit. This comet ATLAS is still inbound though, and will make its perihelion passage on October 8.
© Adam Block