Free Astronomy Magazine September-October 2021

SEPTEMBER-OCTOBER 2021 Giant comet found in outer solar system by NOIRLab - Amanda Kocz A giant comet has been dis- covered by two astronomers following a comprehensive search of data from the Dark Energy Survey (DES). The comet, which is es- timated to be 100–200 kilometers across, or about 10 times the diame- ter of most comets, is an icy relic flung out of the Solar System by the migrat- ing giant planets in the early history of the Solar System. This comet is quite unlike any other seen before and the huge size estimate is based on how much sunlight it reflects.