Another quick report on quick phenomenon, courtesy of Astronomers’ Telegram:
www.astronomerstelegram.org/?read=17551
Serra-Ricart, M. Licandro,J. Alarcon, M. R. Post-perihelion Sunward Tail Detected on Interstellar Comet 3I/ATLAS: A Geometric Projection of the Dust Tail
ATel #17551; 19 Dec 2025; 11:54 UT
Comets have not just one tail, but often two, three, or [multi-]. The smallest “particles” (molecules and ions) are blown about by the solar wind and interplanetary magnetic field. The heaviest ones (pebbles, cobbles, the occasional boulder) are too heavy to blow, and retain the comet’s original orbit- in other words, they trail behind the nucleus. In between, dust particles can continue to form additional tails; in some case the comet has an entire fan, like a peacock or turkey. Our interstellar fellow traveler is no exception:
“Projection-induced sunward tails are well known in solar system comets, but this detection demonstrates that interstellar comets can exhibit comparable dust-tail geometries when observed under favorable viewing conditions.”
Comparable and well known- yes, ATLAS is a comet, folks.