Interstellar comet 3I/ATLAS makes its closest approach to Earth on Dec. 19. Here's how you can track its progress both during the pass and as it races out of the solar system on its way to interstellar space, never to be seen again.
3I/ATLAS was discovered on July 1 earlier this year by astronomers using the Asteroid Terrestrial-impact Last Alert System (ATLAS) survey telescopes, which scan the night sky in search of moving objects that could one day pose a threat to Earth.
