First-known interstellar visitor is a bizarre, cigar-shaped asteroid

Enlarge / An artist's impression of the oddly shaped interstellar asteroid `Oumuamua. (credit: ESO/M. Kornmesser)

Since mid-October, the astronomy community has been buzzing about what might be our Solar System's first confirmed interstellar visitor. An automated telescope spotted an object that appeared as if it had been dropped on the Solar System from above, an angle that suggests it arrived from elsewhere. Now, a team of astronomers has rushed out a paper that describes the object's odd properties and gives it the name "1I/2017 U1 'Oumuamua." In Hawaiian, 'Oumuamua roughly means "first messenger," and the 1I indicates that it's the first interstellar object.

'Oumuamua was first spotted on October 19 by the Pan-STARRS1 automated telescope system. Pan-STARRS1 turned out to have captured images of the object the day previously, but the automated analysis software hadn't identified it. Further images over the next few days allowed researchers to refine its travel through our Solar System, confirming that 'Oumuamua was making the most extreme approach toward the inner Solar System of any object we've ever seen. In essence, it appeared to have been dropped onto the Solar System from above, plunging between the Sun and the orbit of Mercury. It was also moving extremely quickly.

The Solar System was formed from a flattened disk of material, and all of the planets orbit roughly in the plane of that disk. Smaller objects, like dwarf planets and comets, may take somewhat more erratic approaches with orbits tilted out of that plane, but they still roughly aligned with it. We had literally never seen anything like 'Oumuamua.

Read 8 remaining paragraphs | Comments