Ancient interstellar visitor 3I/ATLAS could be a 10–12 billion-year relic from the Milky Way
New JWST/NIRSpec analysis of interstellar comet 3I/ATLAS finds an unusually low carbon-13 to carbon-12 ratio and significant deuterium enrichment, implying it formed very early in the Milky Way’s history. Modeling suggests 3I/ATLAS may be 10–12 billion years old, potentially originating from a thick-disk star system, making it one of the oldest interstellar visitors and perhaps a relic from a vanished stellar neighborhood. The age estimate is not yet peer‑reviewed and is available via a preprint, with researchers noting ongoing uncertainty but tantalizing clues about ancient planet formation beyond our galaxy.