Interstellar comet 3I/ATLAS may be up to 12 billion years old, study finds
Observations with the James Webb telescope and ALMA suggest the interstellar comet 3I/ATLAS is far older than the Solar System and has a composition unlike any known Solar System body.
The interstellar comet 3I/ATLAS, which passed the Sun in 2022, appears to be up to 12 billion years old, making it potentially three times older than the Solar System, researchers reported. The age estimate is based on isotopic measurements taken by the James Webb Space Telescope and the ALMA observatory, which indicate a composition markedly different from Solar System comets.
"maybe it's the oldest object to have been observed in our Solar System," said Martin Cordiner, lead author of the study and a scientist at NASA's Goddard Space Flight Center.
The comet contains roughly 30 times more deuterium than typical Solar System comets, a signature that, according to current astrochemical models, forms only in extremely cold environments. The isotopic evidence points to formation temperatures around minus 243 degrees Celsius, suggesting the object originated in a very cold region of the Milky Way billions of years ago.
Cordiner noted that the comet likely spent billions of years traveling through interstellar space before entering the Solar System, and its lack of chemical enrichment implies formation near newly born stars, possibly during a period known as "cosmic noon" when star formation was at its peak.
The study also addressed earlier speculation that the object could be of artificial origin. NASA and the SETI Institute have found no evidence supporting such claims, and observations are consistent with a natural astrophysical object.
"All observations of the comet are consistent with it being a natural astrophysical object," said Steve Croft of the SETI Breakthrough Listen Initiative.
Other astronomers highlighted the significance of the findings, noting that previous interstellar visitors, 1I/'Oumuamua and 2I/Borisov, were not bright enough to allow similar isotopic analysis. The researchers expect that upcoming facilities, such as the Vera C. Rubin Observatory, will increase detections of interstellar objects, opening a new field of study about the galaxy's composition and history.
"This is just the beginning of an exciting new field, we've got a lot more to learn about these things -- and what they can tell us about our galaxy," Cordiner concluded.