Interstellar comet 3I/ATLAS may date back 12 billion years, study finds

The interstellar object designated 3I/ATLAS, the third known visitor from outside the Solar System, has been identified as potentially originating from a planetary system that existed roughly 12 billion years ago. Researchers analyzed isotopic ratios of hydrogen and carbon on the comet’s surface using data from NASA's James Webb Space Telescope and found signatures that differ markedly from any known Solar System bodies.

The comet contains about ten times more deuterium than any comet studied to date, and its carbon isotopic composition exceeds typical values found in both Solar System comets and nearby interstellar clouds. These extreme isotopic signatures point to formation at temperatures near 30 kelvin (approximately –243 °C) in a relatively metal-poor environment.

"Here we report isotopic measurements of the interstellar comet 3I/ATLAS, which reveal an elemental composition unlike any Solar System body," the authors wrote in a paper published in Nature.

Based on the carbon isotopic data, the team estimates that the object accreted around 12 billion years ago, following a period of intense early star formation in its host system. The findings suggest that 3I/ATLAS is a preserved fragment of an ancient planetary system, predating the formation of our own Sun and planets. The SETI Institute has previously reported no evidence of artificial signals from the comet after extensive radio observations.