Overview
- An MPC circular (MPEC 2025-U142) on Oct. 24 formalized coordinated monitoring and placed 3I/ATLAS at the center of an IAWN comet astrometry campaign running Nov. 27, 2025 to Jan. 27, 2026.
- 3I/ATLAS is confirmed on a hyperbolic path as the third known interstellar visitor, first reported July 1 by the ATLAS survey in Chile, with perihelion expected around Oct. 29–30 at roughly 210 million kilometers from the Sun.
- NASA and partner agencies state there is no Earth impact risk, with closest approach to our planet projected near 1.8 astronomical units, or about 270 million kilometers.
- Astronomers report unusual signatures such as an anti-tail and a bright forward region, while separate claims of pure-nickel ejecta and weak radio pulses remain preliminary and unconfirmed.
- Hubble, JWST, SPHEREx and other assets have imaged the object, and IAWN is organizing workshops to standardize comet astrometry because extended comae can bias centroid measurements.