The new mystery of comet 3I Atlas: Scientists discovered that it is ‘drunk’

This realization provides a rare insight into the chemical conditions that prevail in distant planetary systems and offers us the opportunity to peer into the processes of planet formation outside our home.

Fingerprint of another Sunč system

Using the huge ALMA (Atacama Large Millimeter/submillimeter Array) radio telescope system in Čile, a team of scientists observed the comet at the end of 2025 as it approached the Sun. As the Sun’s light warmed its frozen surface, the ice began to turn directly into gas, creating the vaporized cloud of gas and dust known as a coma. By analyzing this cloud, astronomers can identify the chemical “fingerprints” of the substances from which the comet is made.

The lead author of the research, Nathan Roth from the American University, vividly described the validity of this observation.

​- Looking at 3I/ATLAS is like taking a fingerprint from another Sunč system. “The details reveal what it’s made of, and it’s full of methanol in a way we don’t normally see in comets in our system,” Roth said.

An unusual chemical signature

The research team focused on two molecules that are often found in comets: methanol, a simple alcohol, and hydrogen cyanide, an organic compound that contains nitrogen. The data revealed that the ratio of methanol to hydrogen cyanide was between 70 and 120, making 3I/Atlas among the most methanol-rich comets ever studied.

This unusually high ratio strongly suggests that the icy material from which 3I/Atlas was formed formed under chemical conditions significantly different from those that formed most comets in our Solar System. It probably came from an area that was much colder, which enabled the efficient creation and preservation of methanol-rich ice. Earlier observations by the James Webb Space Telescope also contribute to this unusual chemical profile, which showed that the comet’s coma was dominated by carbon dioxide while it was further away from the Sun.

“Mini-comets” in the dust cloud

The high resolution of the ALMA telescope enabled scientists to study how different molecules are released from comets. It was shown that hydrogen cyanide mostly evaporates directly from the nucleus, which is a common behavior for comets from our system as well. Methanol, however, shows a different dynamic.

He broke free from the core, but also from the tiny, icy dust grains floating inside the coma. These small grains act like a kind of “mini-comets”. As the Sun heats them, their ice turns into gas, releasing additional amounts of methanol into the surrounding cloud. Although similar behavior has been recorded before, this is the first time that scientists have followed the processes of gas evaporation from an interstellar object in such detail.