New NASA data reveals 3I/ATLAS is one of the most mysterious comets ever found

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New NASA data reveals 3I/ATLAS is one of the most mysterious comets ever found
Ariana Garcia
Mon, December 8, 2025 at 6:03 PM EST
3 min read



NASA's Hubble Space Telescope reobserved interstellar comet 3I/ATLAS Nov. 30, with its Wide Field Camera 3 instrument. (NASA, ESA, STScI, D. Jewitt (UCLA), M.-T. Hui (Shanghai Astronomical Observatory). Image Processing: J. DePasquale (STScI))


New observations of the interstellar comet 3I/ATLAS, an object that originated around another star, are revealing just how unusual it really is.

As the comet heads toward its closest pass by Earth, a team led by NASA astrochemist Martin Cordiner used the Atacama Large Millimeter Array (ALMA) in Chile to study the gases streaming off its surface. They found extremely high amounts of methanol and hydrogen cyanide, two molecules tied to the chemistry that helps form the building blocks of life.

"Molecules like hydrogen cyanide and methanol are at trace abundances and not the dominant constituents of our own comets," Cordiner told New Scientist. "Here we see that, actually, in this alien comet they're very abundant."

ALMA's data showed that both chemicals are coming from the comet's solid core, but methanol is also being released from icy grains floating in the cloud of dust and gas surrounding it. About eight percent of all the vapor coming off 3I/ATLAS is methanol-roughly four times the amount typically found in comets from our solar system. The team described the production of both chemicals as "among the most enriched values measured in any comet."

Cordiner noted that this strong chemical activity hints at even more complex reactions happening inside or around the comet. "It seems really chemically implausible that you could go on a path to very high chemical complexity without producing methanol," he said.

Because interstellar comets are leftovers from other planetary systems, these findings offer a rare glimpse into the chemistry of worlds that formed around other stars. Some scientists have even suggested that objects like 3I/ATLAS could have carried life's ingredients to Earth long ago.



In November, ESA's Jupiter Icy Moons Explorer (JUICE) used five of its science instruments to observe 3I/ATLAS. (ESA/Juice/NavCam)


Harvard astronomer Avi Loeb, who has long argued-controversially-that 3I/ATLAS might be alien technology, responded to the new data in a characteristically bold way. "The anomalously large ratio of methanol to hydrogen-cyanide production by 3I/ATLAS suggests a friendly nature for this interstellar visitor," he wrote in one of his latest blog posts.

While scientists examine the comet's chemistry, telescopes across the solar system are capturing dramatic new images. NASA's Hubble Space Telescope photographed 3I/ATLAS on Nov. 30 from about 178 million miles away, its second look since the comet's discovery in July.

The European Space Agency's Jupiter Icy Moons Explorer (JUICE) spacecraft also observed the comet between Nov. 2 and Nov. 25, catching it in what the agency described as a "very active state" after its closest approach to the Sun on October 30. An image taken on Nov. 2-two days before JUICE passed within roughly 41 million miles-shows the comet glowing with a bright coma and sporting two distinct tails, one made of electrically charged gas and the other of drifting dust.

These new views follow NASA's Nov. 19 release of never-before-seen images of 3I/ATLAS. The comet poses no threat to Earth and will make its closest pass-about 170 million miles away-on Dec. 19.

This article originally published at New NASA data reveals 3I/ATLAS is one of the most mysterious comets ever found.