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The\u202fX-Ray Imaging and Spectroscopy Mission (XRISM) observed\u00a0the interstellar comet 3I\/ATLAS for 17 hours between 26\u201328 November 2025.\u00a0\u00a0<\/p>\n
3I\/ATLAS is the first interstellar\u00a0comet\u00a0to have been imaged in\u00a0X-ray\u00a0light.\u00a0Whether\u00a0interstellar\u00a0comets\u00a0shine in\u00a0X-rays as we are used to from\u00a0comets\u00a0originating within\u00a0the Solar System, or whether they\u00a0exhibit\u00a0entirely\u00a0different characteristics,\u00a0has\u00a0remained\u00a0a long-standing mystery.\u202f\u00a0<\/p>\n
The\u00a0X-ray image of the comet\u00a0you see here was\u00a0captured by\u00a0XRISM\u2019s\u00a0soft X-ray telescope Xtend. The field of view covers a region of about 3 million km\u00b2, revealing\u00a0X-rays\u00a0coming\u00a0from a region of around\u00a0400\u00a0000 km around the comet nucleus.\u202fThis\u00a0could\u00a0be caused by a diffuse cloud of gas surrounding the comet, although it requires further analysis.\u00a0<\/p>\n
XRISM\u2019s X-ray image can be compared to that of\u00a0the European Space Agency\u2019s\u00a0XMM-Newton, which also saw a diffuse X-ray glow around the comet.\u00a0\u00a0<\/p>\n
These X-rays can come from the interaction of the solar wind with gases\u00a0from the comet, such as\u00a0water vapour, carbon dioxide, or carbon monoxide. Analysis of XRISM\u2019s data from around the comet nucleus shows signs of carbon,\u00a0nitrogen\u00a0and oxygen.\u00a0\u00a0<\/p>\n
Read the full XRISM\u00a0web story\u00a0here.\u00a0<\/p>\n
For the latest updates and FAQs related to comet 3I\/ATLAS, see\u202fesa.int\/3IATLAS.\u00a0<\/p>\n
XRISM (pronounced\u00a0krizz-em) is a mission led by the Japan Aerospace Exploration Agency (JAXA) in partnership with NASA and ESA. It carries two instruments: an X-ray calorimeter called Resolve capable of measuring the energy of individual X-ray photons to produce a spectrum at unprecedented level of \u2018energy resolution\u2019 (the capability of an instrument to distinguish the X-ray \u2018colours\u2019), and a large field-of-view X-ray CCD camera to image the surrounding field called Xtend.\u00a0<\/i><\/p>\n
[Image description:<\/i>\u00a0This image shows an X-ray view of interstellar comet 3I\/ATLAS, captured by\u00a0the JAXA-led XRISM\u00a0spacecraft.\u00a0Against a black background, purple-to-green blobs appear throughout the image. Around the centre-right of view, a larger, bright green blob stands out \u2013 this is the X-ray light coming from near the comet\u2019s nucleus.\u00a0A\u00a0red\u00a0arrow labelled \u201cSun\u00a0direction\u201d points left, and a yellow arrow labelled \u201ccomet motion\u201d points to the right. At the bottom, a scale marker reads \u201c38.5\u00a0arcmin\u00a0~ 3,000,000 km\u201d,\u00a0while a white circle labelled \u201cr = 5 arcmin ~ 400,000 km\u201d surrounds the bright comet blob.]\u00a0<\/p>\n<\/p><\/div>\n<\/p><\/div>\n