Overview
- JAXA’s XRISM observed 3I/ATLAS Nov. 26–28 for 17 hours and reports a preliminary faint X‑ray glow extending about 400,000 km, with carbon, nitrogen and oxygen features consistent with charge‑exchange in the coma.
- Chemistry reports include unusually high methanol and HCN seen by ALMA and JWST, early University of Hawaii spectra confirming Ni and CN emissions with largely stable colors, and Lowell data indicating gas ratios within the broad range of known comets.
- A coordinated campaign has imaged the visitor across the solar system, including Hubble observations on Nov. 30 and ESA’s Juice flyby data from Nov. 4 that suggest distinct plasma and dust tails, alongside views from PUNCH, Lucy, MAVEN and Perseverance.
- Researchers are tracking non‑gravitational acceleration and debated tail geometry, while NASA states there is no evidence of engineering or propulsion and characterizes the object’s behavior as cometary.
- The third confirmed interstellar object will pass Earth on Dec. 19 at roughly 1.8 AU (about 270 million km), posing no threat and remaining too faint for naked‑eye viewing, with observers advised that large telescopes are required.