On Friday (Dec. 19), the interstellar invader, comet 3I/ATLAS, made its closest approach to Earth, coming to within 168 million miles (270 million kilometers) of our planet at 1 a.m. EST (0600 GMT).
Following this close approach and the opportunity it offers to investigate this interloper from beyond the solar system, 3I/ATLAS will begin to move back out to the outer regions of the solar system, before leaving altogether to continue its voyage through the Milky Way.
3I/ATLAS is just the third body discovered passing through the solar system from interstellar space, its predecessors being 1I/’Oumuamua in 2017 and comet 2I/Borisov in 2019. As such, 3I/ATLAS has been offering scientists the unique opportunity to study the raw materials that came together to form comets, asteroids, and planets orbiting stars other than the sun.