Meet Oumuamua, Earth’s First Interstellar Visitor

Our interstellar visitor — a red and extremely elongated, cigar-shaped asteroid from another galaxy — has a name, Oumuamua, which means we can all stop referring to it as “that freaky fast thing that buzzed Earth” or by the nondescript entry by the International Astronomical Union that catalogued the historic discovery “A/2017 U1.”

In Hawaiian culture, “Oumuamua” is loosely translated to “a messenger that reaches out from the distant past” — an apt name given the watershed nature of its discovery in October by a Pan-STARRS 1 telescope trained over the volcano Haleakala on the Hawaiian island of Maui. It was the first-ever confirmation that an object from another galaxy had entered our solar system.

Astronomers have long predicted such an occurrence, but it wasn’t expected when Institute for Astronomy postdoctoral researcher Rob Weryk began reviewing the Oct. 19 images captured by the telescope.

At first, he and his colleagues thought the faint light zooming through space was a comet or asteroid from Earth’s solar system, but its hyperbolic orbit suggested it came from another galaxy, according to a study published this week in the journal Nature. The study’s authors called the asteroid an “oddball.”

The rapidly rotating asteroid was “at least the size of a football field” and “changed in brightness quite dramatically,” said lead study author Karen Meech, an astronomer at the Institute for Astronomy who specializes in small bodies and their connection to solar system formation.

“This thing is very strange,” Meech said, nothing “the change in brightness hints that Oumuamua could be more than 10 times longer than it is wide – something which has never been seen in our own solar system.”

Meech and the research team say Oumuamua’s dark-reddish hue is the result of millions of years of radiation from cosmic rays and is similar to the color of objects found in the Kuiper Belt, a disc-shaped region of icy bodies and comets beyond the orbit of Neptune on the outer rim of our solar system. The study’s authors said Oumuamua likely has a high metal content and spins on its own axis every eight hours or so.

Scientists and astronomers are giddy about the discovery and think it carries secrets to how other solar systems formed. When our system was formed, the orbit of the largest planets spit out comets and asteroids, and researchers think the same thing likely happened when other planetary systems formed.

"For decades we've theorized that such interstellar objects are out there, and now — for the first time — we have direct evidence they exist," Thomas Zurbuchen, associate administrator for NASA's Science Mission Directorate, said in a statement. "This history-making discovery is opening a new window to study formation of solar systems beyond our own."

Interstellar asteroids probably aren’t that uncommon, according to the researchers, who say there may be as many as 10 a year, but they travel so fast they escape detection.

Oumuamua remains a riddle to be solved. Researchers know it came from the direction of Vega, a bright star in the constellation Lyra, but say Vega was in a different place 300,000 years ago and Oumuamua could have wandered through our Milky Way galaxy for hundreds of millions of years without attaching to any star system before reaching our solar system.

NASA Planetary Defense Officer Lindley Johnson said researchers were fortunate the telescope was pointed in the right place at the right time “to capture this historic moment.”

“This serendipitous discovery is bonus science enabled by NASA’s efforts to find, track and characterize near-Earth objects that could potentially pose a threat to our planet,” he said in a statement.

Oumuamua came so close to the sun that it should have burned up, but didn’t, the researchers said. It could have damaged any celestial body it crossed paths with as it plunged toward the sun, but it did not have any close encounters with the eight major planets in our solar system, scientists said.

Scientists are keeping a close eye on Oumuamua with ground- and space-based telescopes, like Hubble and Spitzer. Oumuamua is currently about 124 million miles from Earth in a trajectory that has taken it past Mars’ orbit. It is hurtling toward Jupiter, which it is expected to pass in May. It is expected to go beyond Saturn’s orbit in January 2019 before exiting the solar system, and appears bound for the Pegasus constellation.

Watch more below:

See Also: Something ‘Very Odd’ Buzzes Earth, Speeds Away

Photo by European Southern Observatory/M. Kornmesser, via NASA