彗星C/2017 K2 （PanSTARRS）
(原标题: Comet C/2017 K2 (PanSTARRS))
2022-06-30
浏览次数: 19
摄于2022年6月20日，彗星C/2017 K2 （PanSTARRS）与疏散星团IC 4665和明亮的蛇夫座β星共享这张宽望远镜视野，靠近银河系的星光边缘。2017年5月，在从昏暗而遥远的奥尔特云前往太阳系内部的处女航中，这颗PanSTARRS彗星最初被发现于5年前。当时，它是迄今为止发现的最遥远的活跃彗星，当时它距离太阳约24亿公里。这使得它的轨道距离介于天王星和土星之间。哈勃太空望远镜的观测表明，这颗彗星的彗核直径不到18公里。现在在小型望远镜上可以看到C/2017 K2将在7月14日最接近地球，并在今年12月最接近太阳。它延伸的彗发和正在发展的彗尾在2.9亿公里的距离上被看到，距离我们只有16光分。
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Imaged on June 20 2022, comet C/2017 K2 (PanSTARRS) shares this wide telescopic field of view with open star cluster IC 4665 and bright star Beta Ophiuchi, near a starry edge of the Milky Way. On its maiden voyage to the inner Solar System from the dim and distant Oort cloud, this comet PanSTARRS was initially spotted over five years ago, in May 2017. Then it was the most distant active inbound comet ever found, discovered when it was some 2.4 billion kilometers from the Sun. That put it between the orbital distances of Uranus and Saturn. Hubble Space Telescope observations indicated the comet had a large nucleus less than 18 kilometers in diameter. Now visible in small telescopes C/2017 K2 will make its closest approach to planet Earth on July 14 and closest approach to the Sun this December. Its extended coma and developing tail are seen here at a distance of some 290 million kilometers, a mere 16 light-minutes away.
© Jose J. Chambo