Overview
- A peer‑reviewed study published June 22 in Nature reports that high‑resolution spectra of 3I/ATLAS show about 30 times more deuterium than Solar System comets and only trace amounts of carbon‑13.
- Scientists interpret those isotope ratios as a sign the comet condensed at very low temperatures in a metal‑poor region of the galaxy roughly 10 to 12 billion years ago, though that age depends on chemical‑evolution and condensation models.
- The result comes from a coordinated observational campaign using JWST’s NIRSpec plus ground telescopes including ALMA and the VLT that measured gases released from the comet’s coma after its 2025 perihelion.
- 3I/ATLAS was unusually large and bright for an interstellar visitor, which allowed detailed study; it is now on a hyperbolic path leaving the Solar System and cannot be reobserved at the same signal strength.
- Researchers say the finding gives a rare direct data point about early galactic chemistry, raises questions about how common life‑friendly chemistry may be, and will prompt more modeling and comparisons with other comets.