Comet C/2014 UN271 Bernardinelli-Bernstein, the largest comet ever discovered, was already exhibiting coma at heliocentric distances 23.8 and 21.2 AU, making it one of the most distant comets for which preperihelion activity has been directly detected, according to a new analysis of data from NASA’s Transient Exoplanet Survey Satellite (TESS). Coadded images of comet Bernardinelli-Bernstein (C/2014 UN271) from 2018 and 2020, showing coma with a...
