NASA Releases Close-Up Images of Interstellar Comet 3I/ATLAS — CO2-Rich and Manhattan-Sized

NASA has released new close-up images and data of 3I/ATLAS, a large comet that originated beyond our solar system and is passing through at extraordinary speed. Observations from Mars orbiters, Hubble and the James Webb Space Telescope reveal a carbon dioxide–rich coma and suggest the object may be between about 1,400 feet and 3.5 miles across.

Images unveiled at a press briefing at NASA’s Goddard Space Flight Center were captured in early October by the HiRISE camera on the Mars Reconnaissance Orbiter and by instruments on the MAVEN Mars orbiter when 3I/ATLAS was tens of millions of miles from Mars (reported distances of roughly 18.6 million and 35 million miles). NASA also released an additional image taken in mid-October by the joint ESA–NASA Solar and Heliospheric Observatory.

"I would like to address the rumors right at the beginning. I think it's important that we talk about that. This object is a comet. It looks and behaves like a comet, and all evidence points to it being a comet. But this one came from outside the solar system, which makes it fascinating, exciting and scientifically very important," said NASA Associate Administrator Amit Kshatriya.

What we know

3I/ATLAS was first detected on July 1 by the Asteroid Terrestrial-impact Last Alert System (ATLAS), which is reflected in its name. Follow-up observations from Hubble refined size estimates to a broad range — roughly 1,400 feet to 3.5 miles — while JWST found the comet’s coma to be dominated by carbon dioxide with additional water and ice.

Unusual composition and why it matters

Researchers analyzing early data report an unusually high carbon dioxide-to-water ratio for an object this far from the Sun — among the highest measured in any comet. That composition differs from most comets formed in our solar system and could indicate that 3I/ATLAS formed in a CO2-rich region of another planetary system or experienced stronger radiation exposure during its history.

"We were quick to be able to say, yep, it definitely behaves like a comet... But the super cool thing is not that it's exactly like all the comets that we see in our solar system. It's the differences that are so tantalizing," said Nicky Fox, associate administrator of NASA's Science Mission Directorate.

Trajectory and timeline

NASA reports that 3I/ATLAS reached perihelion (closest approach to the Sun) on Oct. 30 at about 130 million miles and will be nearest Earth on Dec. 19 at roughly 170 million miles. The comet follows a hyperbolic trajectory, meaning it is moving too fast to be captured by the Sun’s gravity and is merely passing through our solar system.

Speculation and next steps

Public discussion and scientific debate have included speculation about whether the object might be artificial or otherwise unusual. Harvard scientist Avi Loeb has pointed to a set of anomalies he believes merit further study. NASA scientists emphasize that, so far, the object behaves like a comet and that multiple interpretations must be tested against additional data.

"I think of these as frozen fossils from their moments of formation... What this will let us do is tell that story in a broader context between the detailed and large library of data we have on those origins of our own solar system," said Shawn Domagal-Goldman, acting director of NASA's Astrophysics Division.

All collected observations and measurements will be released publicly. Researchers plan to scrutinize the data thoroughly and submit analyses to peer-reviewed journals before drawing firm conclusions about the comet’s origin and what it may reveal about other planetary systems.