Something strange sailed past Earth last month, and thanks to some quick work, astronomers managed to get their first good look at a visitor from interstellar space.
Now named ‘Oumuamua, Hawaiian for “a messenger from afar arriving first,” the object is the first known lump of rock and ice from another star system, which gives astronomers a chance to glimpse a scrap left over from an alien planet’s formation.
“This has been crazy-cool. For the asteroid community, this is as big as the gravitational-wave announcement,” NASA astronomer Joseph Masiero said when the object was discovered, referencing the recent detections of ripples in space-time that have been amazing astrophysicists.
And as researchers report today in Nature, the visitor lives up to its exotic origin: The object is at least 10 times longer than it is wide, resembling a giant cosmic pencil tumbling through the void.
“It’s extraordinarily elongated, which is extremely unusual—we don’t see anything like that in our solar system,” says study leader Karen Meech of the University of Hawaii’s Institute for Astronomy.
Rob Weryk, a postdoctoral researcher at the University of Hawaii, first spotted the interstellar interloper on October 19, in an image made by the university’s Pan-STARRS 1 telescope.
When he followed up with European Space Agency astronomer Marco Micheli, the two realized that the object—provisionally called A/2017 U1—was outrunning the sun’s gravitational pull. By the time astronomers confirmed the object’s ballistic flight path, it was exiting the solar system at more than 98,000 miles an hour.
After observing the object on its outbound journey, scientists noted that ‘Oumuamua didn’t spawn a tail of gas or dust as it flew by the sun. That means the interstellar object is likely not a comet, and is instead probably an asteroid that formed in the inner part of another star system.
What a wonderful universe we live in.