Beyond Our Solar System — Massive Interstellar Object 3I/ATLAS Rewrites The Comet Rulebook

As it moves toward its October 30 perihelion, 3I/ATLAS’s coma continues to brighten and shift in hue, now emitting a faint green glow from excited carbon molecules. Some astronomers have called it “a living lab for cosmic chemistry,” while others caution that its unpredictable activity could make it fragment or break apart before the year is over.

Watched by an Entire Fleet

For the first time in history, a single interstellar object is being observed simultaneously by spacecraft at multiple planets. ESA’s Mars orbiters and the JUICE mission heading toward Jupiter are each taking measurements from different vantage points. This multi-angle approach allows scientists to construct a three-dimensional model of its composition and trajectory.

Such coordination marks a new era in planetary defense and deep-space study. “Every agency wants a piece of 3I/ATLAS,” one ESA official said. “It’s not just about curiosity—it’s about understanding how often objects like this cross our path and what they can teach us about alien worlds.”