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

The European Space Agency’s Juice spacecraft is positioned to observe any such plume during the first week of November, while hundreds of ground-based telescopes plus the Hubble and Webb space telescopes will train their instruments on 3I/ATLAS when it makes its closest approach to Earth on December 19, 2025, at a distance of 269 million kilometers.

The acceleration measurements align with troubling observations from September and October 2025 captured by STEREO, SOHO and GOES-19 instruments, which recorded an unusual rapid brightening of the object.

The brightness increased inversely with distance from the Sun to the power of negative 7.5, a relationship that defies typical comet behavior and suggests either massive volatile evaporation or an alternative mechanism entirely. Adding to the mystery, recent reports indicate 3I/ATLAS appeared bluer than the Sun during perihelion, representing the ninth documented anomaly in the object’s already peculiar profile.

Natural comets typically display reddened light from dust scattering, and with surface temperatures expected to reach only one-twentieth of the Sun’s 5,800 degrees Kelvin photosphere, the blue coloration challenges conventional explanations.