Overview

• Telescopic observations reveal that 3I/ATLAS is developing a cometary coma and tail as it heats in the inner solar system.
• It is traveling at about 60 km/s, making it the fastest known interstellar visitor, and spans an estimated 10–20 kilometers in diameter.
• Trajectory analyses project its closest approach at 1.5 AU from Earth and a perihelion inside Mars’s orbit on October 30.
• Backtracking its path points to an origin near the Milky Way’s Galactic Center, suggesting a thick-disk or bulge provenance.
• The European Space Agency is advancing its Comet Interceptor mission, scheduled for launch in 2029, to rendezvous with pristine or interstellar objects.