Overview

• Gemini North’s Multi-Object Spectrograph images revealed a compact coma around 3I/ATLAS’s nucleus, confirming its cometary nature as the third interstellar visitor.
• Global measurements estimate its diameter at about 20 kilometers, dwarfing previous interstellar objects ʻOumuamua and Borisov.
• Its hyperbolic orbit, with an eccentricity of 6.2, ensures an unbound trajectory that brings it closest to the Sun on October 30, 2025.
• The comet will pass approximately 270 million kilometers from Earth on December 19, 2025, posing no impact threat.
• The Vera C. Rubin Observatory’s upcoming LSST is expected to increase detections of similar interstellar objects from just three to dozens over the next decade.