Mysterious Interstellar Object 3I/ATLAS Shows Unprecedented Non-Gravitational Acceleration Near Sun – Harvard Astrophysicist Avi Loeb Says Data Reveals Two-Component Push

The comment, made in the context of cosmological puzzles regarding universe expansion rates, applies directly to the 3I/ATLAS situation. With thermal ejection speeds for natural comets typically reaching only a few hundred meters per second, the documented acceleration demands either unprecedented volatile activity or a reconsideration of the object’s fundamental nature.

What’s Next

The ESA Juice spacecraft observations during the first week of November 2025 will provide the initial crucial data on whether massive gas plumes surround 3I/ATLAS, offering the first test of the natural outgassing hypothesis.

The definitive observational window arrives December 19, 2025, when 3I/ATLAS reaches its closest point to Earth, allowing multiple space telescopes and hundreds of ground-based observatories to conduct detailed spectroscopic analysis, thermal imaging and mass-loss measurements.

These observations will determine whether the object lost approximately ten percent of its mass during perihelion passage, effectively resolving whether conventional comet physics can account for the non-gravitational acceleration or whether the scientific community must confront more extraordinary possibilities.