Overview
- A coordinated study published in Nature on June 22, 2026, combined JWST NIRSpec data with ALMA and VLT measurements to produce the first high‑fidelity isotopic readout of an interstellar object.
- Webb detected water with about 30 times the deuterium found in typical Solar System comets, a heavy‑hydrogen excess that points to formation at very low temperatures.
- The team also found only trace carbon‑13 relative to carbon‑12, and used those isotope ratios with chemical evolution models to estimate a formation age of roughly 10–12 billion years.
- Scientists caution the age and composition inferences depend on models and on reading coma gases rather than the hidden nucleus, but they say the result challenges the idea that Solar System comets are a universal template.
- The rapid, multi‑facility follow up on 3I/ATLAS — the third confirmed interstellar visitor — shows the value of coordinated space and ground telescopes and raises the stakes for future finds from surveys like the Rubin Observatory.