2025年12月26日
3I/ATLAS Flyby
Image Credit & Copyright: Dan Bartlett
Explanation: Attention grabbing interstellar visitor 3I/ATLAS made its not-so-close flyby of our fair planet on December 19 at a distance of 1.8 astronomical units. That’s about 900 light-seconds. This deep exposure captures the comet from another star system as it gently swept across a faint background of stars in the constellation Leo about 4 days earlier. Though faint, colors emphasized in the image data show off the comet’s yellowish dust tail and bluish ion tail along with a greenish tinged coma. And even as it is scrutinized by arrays of telescopes and spacecraft from planet Earth, 3I/ATLAS is headed out of the Solar System. It’s presently moving outward along a hyperbolic trajectory at about 64 kilometers per second relative to the Sun, too fast to be bound by the Sun’s gravity.
Tomorrow’s picture: Apollo’s Moonship
3I/ATLAS近掠事件
影像提供与版权: Dan Bartlett
说明: 引人注目的星际访客3I/ATLAS于12月19日以1.8天文单位的距离掠过我们美丽的星球。这大约相当于900光秒。尽管如此，这张深度曝光照片捕捉到了这颗来自另一个恒星系统的彗星，它大约在4天前的12月15日晚上，轻轻掠过狮子座一片昏暗的星空背景。虽然影像很暗淡，但影像资料中色彩的增强，展现了彗星淡黄色的尘埃尾、淡蓝色的离子尾以及略带绿色的彗发。即使地球上的望远镜和航天器阵列都在仔细观察，3I/ATLAS正朝着太阳系外进发。它目前正沿着双曲线轨道向外移动，相对于太阳的速度约为每秒64公里，速度之快，使其无法被太阳的重力束缚。
明日的图片: Apollo’s Moonship
