Overview

• 3I/ATLAS is the third confirmed interstellar object, discovered by the NASA-funded ATLAS survey on July 1, 2025 and cataloged by the Minor Planet Center.
• The comet passed Mars on October 3 and will slip behind the Sun in late October, with viewing from Earth expected to resume on the far side in early December.
• Hubble, the James Webb Space Telescope and SPHEREx are tracking its activity, with Mars orbiters contributing observations during the recent flyby.
• Its speed was about 61 km/s at discovery and is increasing toward perihelion around October 30 just inside Mars’s orbit, before an outbound pass by Jupiter in March 2026.
• NASA estimates the nucleus is no wider than roughly 3.5 miles, and although some have speculated about exotic origins, agencies describe it as a natural comet that poses no hazard.