Astronomers have spotted something unusual in a comet passing through our Solar System. 3I/ATLAS, only the third confirmed interstellar visitor ever seen, appears to be stuffed with methanol, an alcohol you might find in a lab, not your drink. Using the Atacama Large Millimetre/submillimeter Array (ALMA) in Chile, researchers reportedly measured methanol at levels far higher than those of hydrogen cyanide, a molecule usually common in comets.It seems 3I/ATLAS isn’t like the comets we’re used to. Its icy core and surrounding coma reveal chemical conditions that might hint at how planets form in other solar systems. Experts say this could be a rare peek into alien planetary chemistry, something scientists have been waiting decades to study. The comet, glowing as it neared the Sun, gave off telltale signals that ALMA could detect.
Comet 3I/ATLAS: ALMA detects higher levels of methanol than expected
The numbers are striking. On two separate observations, the methanol-to-HCN ratio was reportedly around 70 and 120. That’s huge compared to most comets from our own system, where methanol is usually far less dominant. Nathan Roth, the lead researcher and professor at American University, called it like taking a fingerprint from another solar system. And it seems this fingerprint is rich. Really rich.The ALMA Morita Array, sometimes called the Atacama Compact Array (ACA), tracked the comet over several days in late 2025. As sunlight warmed its icy surface, 3I/ATLAS released gas and dust. This created a glowing halo or coma around its nucleus. By analysing this haze, scientists could see exactly what chemicals were present. Methanol popped out, far more than anyone expected.
Comet 3I/ATLAS reveals methanol patterns not seen in Solar System comets
Interestingly, methanol behaves differently from other molecules in the coma. Hydrogen cyanide seems to come mostly from the nucleus, like in typical Solar System comets. Methanol, on the other hand, appears to be released both from the nucleus and tiny icy grains floating in the coma. These grains act like mini-comets, releasing methanol when sunlight hits them.It’s a curious thing. Some Solar System comets do this, but seeing it in an interstellar object is new. It might suggest that 3I/ATLAS formed or was processed under conditions unlike anything here at home. The James Webb Space Telescope had already hinted at something odd, finding carbon dioxide dominating the coma at larger distances from the Sun. Methanol just adds another layer of mystery.
Comet 3I/ATLAS offers a glimpse into distant planetary chemistry
Every interstellar visitor is a snapshot of a distant planetary system. 3I/ATLAS follows 1I/‘Oumuamua and 2I/Borisov, both of which sparked huge scientific interest. These objects might be rare, but each carries clues about how planets and comets form across the galaxy. Seeing such a methanol-rich comet gives astronomers a chemical window into places we’ll never visit.Observing 3I/ATLAS also helps refine models of comet chemistry. It seems that different star systems might produce wildly different mixes of ice and organics. That could change the way we think about planet formation, even hinting that some systems are more “chemical cocktails” than the neat Solar System we know.
