The first known interstellar object, 'Oumuamua, was discovered

On October 19, 2017, the Pan-STARRS1 telescope on Haleakala, Hawaii, picked up a faint point of light moving on a strange path. Within days astronomers realized its orbit was hyperbolic — too fast and too open to be bound to the Sun. It had come from interstellar space, the first such visitor ever confirmed.

Its discoverers named it ‘Oumuamua, Hawaiian for roughly “a messenger from afar arriving first.” The object was deeply puzzling: highly elongated, perhaps 400 meters long and around ten times longer than it was wide, a shape unlike any asteroid or comet seen at home.

For decades scientists had predicted such wanderers existed. Here, at last, was one.

‘Oumuamua had already rounded the Sun in early September and was speeding away when found, leaving only a brief window to study it. It never came back, but it proved that fragments of other star systems do drift through our own — and that we can catch them in the act.