3I/ATLAS: ESA’s XMM-NEWTON Caught The Exocomet Under X-ray Light; Here's What It Found

The European Space Agency (ESA) released x-ray imagery of 3I/ATLAS, the third-ever recorded interstellar interloper in the solar system after 1I/Oumuamua (2017) and 2I/Borisov (2019). The portrait of the exocomet was taken by ESA’s XMM-Newton observatory via its European Photon Imaging Camera (EPIC)-pn camera. The instrument is the most sensitive X-ray camera on the probe that was launched on December 10, 1999. XMM stands for X-ray Multi-Mirror Mission. The name Newton in the instrument is an homage to legendary English physicist and mathematician Sir Isaac Newton. Here’s what the XMM observed
This image shows the comet glowing in low-energy X-rays: blue marks empty space with very few X-rays, while red highlights the comet’s X-ray glow. Astronomers expected to see this glow because when gas molecules streaming from the comet collide with the solar wind, they produce X-rays.
ESA added in its XMM observation
These X-rays can come from the interaction of the solar wind with gases like water vapor, carbon dioxide, or carbon monoxide—which telescopes such as the NASA/ESA/CSA James Webb Space Telescope and NASA’s SPHEREx have already detected. But they are uniquely sensitive to gases like hydrogen (H₂) and nitrogen (N₂). These are almost invisible to optical and ultraviolet instruments, such as the cameras on the NASA/ESA Hubble Space Telescope or ESA’s JUICE.
3I/ATLAS, first spotted by the ATLAS observatory on July 1, 2025 is on its closest approach to Earth by December 19, 2025. All eyes are glued on to the interstellar comet when the observatories will have a clearer view at a distance of 1.79 AU.
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See Also: 3I/ATLAS: Harvard Astrophysicist Avi Loeb Decodes The X-ray Emitted By Exocomet As Spotted By XRISM Xtend
Cover: ESA