哈勃影像: 星际访客3I/ATLAS

2025年8月9日

Interstellar Interloper 3I/ATLAS from Hubble
Image Credit: NASA, ESA, David Jewitt (UCLA) et al. – Processing: Joseph DePasquale (STScI)

Explanation: Discovered on July 1 with the NASA-funded ATLAS (Asteroid Terrestrial-impact Last Alert System) survey telescope in Rio Hurtado, Chile, 3I/ATLAS is so designated as the third known interstellar object to pass through our Solar System. It follows 1I/ʻOumuamua in 2017 and the comet 2I/Borisov in 2019. Also known as C/2025 N1, 3I/ATLAS is a comet. A teardrop-shaped cloud of dust, ejected from its icy nucleus warmed by increasing sunlight, is seen in this sharp image from the Hubble Space Telescope captured on July 21. Background stars are streaked in the exposure as Hubble tracked the fastest comet ever recorded on its journey toward the inner solar system. An analysis of the Hubble image indicates the solid nucleus, hidden from direct view, is likely less that 5.6 kilometers in diameter. This comet’s interstellar origin is clear from its orbit, determined to be an eccentric, highly hyperbolic orbit that does not loop back around the Sun and will return 3I/ATLAS to interstellar space. Not a threat to planet Earth, the inbound interstellar interloper is now within the Jupiter’s orbital distance of the Sun, while its closest approach to the Sun will bring it just inside the orbital distance of Mars.

Tomorrow’s picture: down the road

哈勃影像: 星际访客3I/ATLAS
影像提供: NASA, ESA, David Jewitt (UCLA) et al. – 影像处理: Joseph DePasquale (STScI)

说明: 由位在智利里奥胡塔多镇、受到NASA资助的ATLAS（小行星地球撞击最后警报系统）望远镜，发现于2025年7月1日的3I/ATLAS，是第三颗穿过太阳系的已知星际天体。而先前发现的星际天体有，2017年的斥候星（1I/ʻOumuamua）和2019年的博里索夫彗星（2I/Borisov）。亦名为C/2025 N1的3I/ATLAS，是一颗彗星。在这幅哈勃太空望远镜摄于7月21日的清晰影像里，可见到其冰冷彗核受到阳光加热而喷出的泪滴状尘埃云。影像背景中的恒星在取像期间曳出迹线，这是因为哈勃是以这颗史上最高速朝太阳系内围前进的彗星为导星标的。针对哈勃影像所进行的分析显示，这颗彗星不可见的固态核心，直径可能小于5.6公里。从它偏心、高离心率的双曲线的轨道，可以确定3I/ATLAS将回到星际空间，不会绕行太阳。这位星际访客对地球并无威胁，目前它已经行进到木星的轨道内，而它最接近太阳时，将会靠近到火星的轨道之内。

明日的图片: down the road