Since its discovery in July 2025, it feels like we've seen images of 3I/ATLAS in just about every wavelength of light, and from all manner of different observatories, telescopes and space missions.
We've seen powerful images from ground-based telescopes like the Gemini South telescope and the Very Large Telescope.
We've seen infrared images of 3I/ATLAS from the James Webb Space Telescope.
More on 3I/ATLAS
NASA's fleet of solar-observing missions captured beautiful images of 3I/ATLAS.
Even spacecraft at Mars have seen 3I/ATLAS, as has ESA's Juice mission on its way to Jupiter.
And now, this latest image shows 3I/ATLAS in x-ray light, revealing a view of the interstellar comet like we've never seen before.
An x-ray view of an interstellar visitor
What makes comet 3I/ATLAS so special is that it's an interstellar comet.
The vast majority of comets we observe in the night sky originated from within our own Solar System.
But 3I/ATLAS came from beyond our Solar System, elsewhere in the Galaxy. It's one of only three such objects we've ever seen.
That's why scientists are keen to gather as much information about it before it leaves our Solar System forever.
The European Space Agency’s X-ray space observatory XMM-Newton observed 3I/ATLAS on 3 December 2025 for around 20 hours.
At the time of its observations, the comet was about 285 million km (177 million miles) from the spacecraft.
XMM-Newton used its most sensitve x-ray camera, known as the European Photon Imaging Camera (EPIC)-pn camera.
What the images show
The XMM-Newton image below shows 3I/ATLAS glowing in low-energy x-ray light.
The dim blue points of light indicate empty space with few x-rays, while red shows the comet's x-ray glow.
Gas molecules streamg from the comet as it gets heated by the Sun. These molecules smash into the solar wind – a stream of charged particles emanating from the Sun – causing the glow seen here.
X-rays can be generated from the solar wind interacting with water vapour, carbon dioxide or carbon monoxide, as was seen in the images of 3I/ATLAS taken with the James Webb Space Telescope and the SPHEREx mission, released earlier this year.
But x-rays are sensitive to gases like hydrogen and nitrogen, which are virtually invisible to instruments that observe in optical and ultraviolet wavelengths, like the Hubble Space Telescope or ESA's Juice mission.
That means these x-ray observations are giving scientists a new view of the comet, enabling the detection of gases that otherwise couldn't be seen.
The more we point our telescopes and spacecraft at this mysterious interstellar visitor, the more we learn.
