Our Second Interstellar Visitor Was a 'Dirty Snowball' With Stories to Tell
New research suggests 2I/Borisov-the second known interstellar visitor to our solar system-had never previously visited a star, not even the one from its home system, prior to zipping past our Sun in 2019. That makes Borisov one of the most pristine-if not the most pristine-comet ever observed by astronomers, in what...