Yesterday was Oct. 29, perihelion for 3I/ATLAS. That was the point in its trajectory (not orbit) when it was closest to the Sun. As the comet neared the Sun, it rose in temperature, and thus activity. That activity:
Astrophysics > Earth and Planetary Astrophysics arxiv.org/abs/2510.25035
[Submitted on 28 Oct 2025]
Zhang, Q. Battams, K. Rapid Brightening of 3I/ATLAS Ahead of Perihelion
As I’ve posted, Sun-tracking missions are able to see and follow ATLAS, and are doing so for the next few weeks. This paper describes STEREO, SOHO, and now GOES-19 as Solar observatories coincidentally spotting ATLAS.