It is speeding up: Scientists baffled as mystery asteroid defies all known physics

An 11 metre asteroid called 1998 KY26 is accelerating in an unusual way, with out of plane non gravitational acceleration and a spin of once every 5.35 minutes. One leading theory called it a hidden dark comet using escaping gas to propel itself. New research in Icarus by Korbin Hansen and Masatoshi Hirabayashi shows KY26 is too warm to retain the ice needed for that process. So what is pushing it? Solar radiation pressure, Yarkovsky effect, dust shedding or something unknown. Japan's Hayabusa2 spacecraft will reach it in July 2031 for closer answers. Earlier, 3I/ATLAS, the third interstellar object discovered 1 July 2025, also showed strange non gravitational acceleration after perihelion on 30 Oct 2025.