3I/ATLAS Interstellar Comet: UN Planetary‑Defence Campaign Begins as Mars Data Sharpens Its Path
The United Nations’ planetary-defence network launched a live global drill on 27 November 2025, using interstellar comet 3I/ATLAS as the focus. New spacecraft data near Mars has improved trajectory predictions tenfold. The comet will pass closest to Earth on 19 December at 1.8 AU, posing no threat. The observing campaign runs through 27 January 2026.