Overview
- An IAWN–Minor Planet Center bulletin (MPEC 2025-U142) formalized a global astrometry campaign with a special training exercise scheduled for November 27, 2025 through January 27, 2026.
- 3I/ATLAS is expected to reach perihelion on October 29–30 at roughly 1.36–1.4 AU from the Sun, a window scientists will use to probe its composition and activity.
- Agencies reiterate there is no impact risk, with the closest Earth distance projected at about 1.8 AU (around 270 million km) in December.
- Multi-instrument observations from Hubble, JWST, VLT, Gemini and Keck report unusual features including an anti-tail, very high CO2 relative to water, and strong atomic nickel emissions with little iron.
- Some reports describe weak radio pulses coincident with the trajectory, a claim not widely corroborated and characterized as speculative by researchers.