Astronomers using ESA's XMM-Newton observatory captured the X-ray image 3I/ATLASthird confirmed interstellar object passing through the Solar System, after 1I/Oumuamua and 2I/Borisov.
This XMM-Newton image shows an X-ray image of interstellar comet 3I/ATLAS. In the center of the image, a bright red spot stands out against a dark background, like a fiery beacon. Starting from this core, faint gradients of purple and blue spread outward, creating a slightly rotated rectangular frame separated by a thin horizontal line—the detector gap. Red shows low-energy x-rays, blue represents empty space with very few x-rays. Image credit: ESA/XMM-Newton/C. Lisse/S. Cabot/XMM ISO Team.
On December 3, 2025, the XMM-Newton spacecraft observed the interstellar comet 3I/ATLAS for about 20 hours.
During this time, the interstellar object was at a distance of about 282–285 million km from the spacecraft.
XMM-Newton observed the comet with its European Photon Imaging Camera (EPIC)-PN, the world's most sensitive X-ray camera.
“This XMM-Newton image shows a comet glowing in low-energy X-rays: blue represents empty space with very few X-rays, and red represents the comet's X-ray glow,” the XMM-Newton team said in a statement.
Astronomers expected to see this glow because when gas molecules escaping from the comet collide with the solar wind, they produce X-rays.
“These X-rays may result from the interaction of the solar wind with gases such as water vapor, carbon dioxide or carbon monoxide, which telescopes such as the NASA/ESA/CSA James Webb Space Telescope and NASA SPHEREx have already detected,” they said.
“But they are uniquely sensitive to gases like hydrogen and nitrogen.”
“They are nearly invisible to optical and ultraviolet instruments such as the NASA/ESA Hubble Space Telescope cameras or ESA's JUICE.”
“This makes X-ray observations a powerful tool,” they noted.
“They allow scientists to detect and study gases that other instruments cannot easily detect.”
“Some groups of scientists believe that the first interstellar object discovered, 1I/'Oumuamua, may have been composed of exotic ices such as nitrogen or hydrogen.”
“Although 1I/'Oumuamua is currently too far away, 3I/ATLAS provides a new opportunity to study the interstellar object, and the X-ray observations will complement other observations and help scientists figure out what it's made of.”
