NASA Activates Global Watch on Interstellar Comet 3I/ATLAS Ahead of Oct. 29 Perihelion

Overview

• The International Asteroid Warning Network issued a technical alert (MPEC 2025-U142) and activated monitoring protocols after atypical behavior was logged.
• A targeted training exercise will run from Nov. 27, 2025 to Jan. 27, 2026 to improve comet position measurements and response workflows.
• Early James Webb data indicate an unusually CO2-dominant composition, with extreme negative polarization and elevated nickel with little iron reported by observing teams.
• Observers recorded a flip from a sunward anti-tail to a conventional tail, along with measurable non-gravitational acceleration as the object approaches the Sun.
• Current assessments state no immediate threat to Earth, with trajectory refinements ongoing and projections including future passes by Jupiter, Venus and Mars, while reports of nickel carbonyl emission and probe speculation remain unconfirmed.