Comet 3I/ATLAS May Be an Orphan Older Than the Milky Way

An assessment published this week on the isotopic composition of interstellar comet 3I/ATLAS suggests an intriguing possibility: The comet may be between 10 and 12 billion years old, making it roughly as old as, or even older than, our own Milky Way galaxy.

The paper is available as a pre-print edition awaiting peer review, though the lead authors have all published ample peer-reviewed research in the past. The findings analyze spectrographic data collected by the Near-Infrared Spectrograph on the James Webb Space Telescope.

Specifically, the researchers examined the ratios of the isotopes carbon-12 and carbon-13 in 3I/ATLAS's plume, along with the hydrogen-to-deuterium ratio in the comet's water ice.

The carbon ratio can help narrow down the comet's potential age, as carbon-13 tends to build up over time in the sorts of star-forming clouds that would have originally spit out a comet like 3I/ATLAS. A ...