Overview
- The Minor Planet Center’s MPEC 2025-U142 formalized a coordinated NASA/IAWN monitoring effort for 3I/ATLAS, citing unique challenges in predicting its motion.
- IAWN’s comet astrometry campaign and training exercise will focus on improving centroiding and consistency of measurements from November 27, 2025 to January 27, 2026.
- Perihelion is expected around October 29–30 at roughly 1.36–1.4 AU from the Sun, with optimal Earth-based observations forecast for November and December.
- NASA says the object poses no impact risk, with the closest Earth approach projected at about 1.8 AU (approximately 270 million kilometers) in December.
- Observations by Hubble, JWST, VLT and other facilities report unusual signatures including an anti-tail, a very high CO2-to-water ratio, and strong atomic nickel emission with little iron, which remain under study.