When the faint object now known as 3I/ATLAS was first detected by the ATLAS telescope in Hawaii earlier this year, astronomers classified it as another comet. Within weeks, it became clear that this visitor was far from ordinary. Its trajectory, chemistry and activity patterns have made it one of the most puzzling interstellar objects ever recorded — and, for some, a possible sign of something artificial.
3I/ATLAS is only the third confirmed interstellar object known to have passed through our solar system, following the discoveries of 1I/ʻOumuamua in 2017 and 2I/Borisov in 2019. Its speed and open, hyperbolic orbit indicate that it did not originate from the Sun's gravitational family and will never return once it departs.
