31/Atlas is an alien comet, not an alien craft, even though it is not accelerating due only to gravity. –CPL

Space Weather News for Dec. 16, 2025
https://spaceweather.com

THE NON-GRAVITATIONAL ACCELERATION OF 3I/ATLAS:  New data from NASA’s Psyche spacecraft and ESA’s Mars Trace Gas Orbiter confirm that interstellar comet 3I/ATLAS is not moving under the force of gravity alone. It has a “non-gravitational acceleration.” The effect can be explained entirely by cometary outgassing, and allows astronomers to weigh the comet from afar. Full story @ Spaceweather.com.