‘Oumuamua, First Interstellar Asteroid, Visits From Another Solar System

‘Oumuamua, an interstellar guest to our solar system, graced our skies last October. It is the first known asteroid confirmed to hail from another solar system. Formally designated 1I/2017 U1 according to NASA, the entity has been described as appearing “to be a rocky, cigar-shaped object with a somewhat reddish hue.”

‘OUMUAMUA, THE FIRST KNOWN INTERSTELLAR ASTEROID

‘Oumuamua was discovered on Oct. 19 by the NASA-funded Pan-STARRS1 telescope at the University of Hawaii. It was initially classified as a comet, though it demonstrated no signs of typical comet behavior as it traveled by the sun on Sept. 9 at an impressive speed of 196,000 miles per hour. The asteroid is approximately 400 meters long, “perhaps 10 times as long as it is wide,” giving it dimensions unlike anything previously recorded in our solar system.

Naturally, this unexpected encounter is exciting to scientists. Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate, said, “For decades we’ve theorized that such interstellar objects are out there, and now―for the first time―we have direct evidence they exist.” Karen Meech and her team at Hawaii’s Institute for Astronomy found ‘Oumuamua to be “dense, composed of rock and possibly metals, has no water or ice, and that its surface was reddened due to the effects of irradiation from cosmic rays over hundreds of millions of years.”

The foreign rock might have suffered through a violent altercation at some point in its past as explained by a new paper published in Nature Astronomy. Wesley C. Fraser, one of the scientists working on the paper, cites ‘Oumuamua’s irregular spinning as evidence of how it might have collided with “another planetesimal in its system, before it was ejected into interstellar space.” Fraser adds how “the timescale to damp 1I/‘Oumuamua’s tumbling is at least one billion years. 1I/‘Oumuamua was probably set tumbling within its parent planetary system and will remain tumbling well after it has left ours.”