Interstellar Object Near Earth Detected For First Time

MAUI, HI — Something that was "definitely very odd" buzzed past Earth at about 16 miles per second, which is a freaky fast speed, before it was hurtled into outer space by the sun’s gravity. Astronomers aren't able to explain exactly what it was or how it got this close to Earth, but the University of Hawaii's Institute for Astronomy has put together a team of scientists to try to figure it out.

What is known about the near-Earth space object — and by "near," astronomers mean 15 million miles away, or about 60 times the distance to the moon — is that it wasn't from our solar system, making it the first "interstellar object" ever to be be observed and confirmed by astronomers. That's huge, according to NASA's Paul Chodas, who manages the Center for Near-Earth Object Studies at the agency's Jet Propulsion Laboratory in Pasadena, California.

"We have been waiting for this day for decades," he said in a news release announcing the discovery.

Scientists have long suspected these objects should exist, according to Karen Meech, an astronomer at the Institute for Astronomy who specializes in small bodies and their connection to solar system formation. She said that during the process of planet formation, voluminous amounts of material should be ejected from planetary systems.

"What's most surprising is that we’ve never seen interstellar objects pass through before," Meech said in the news release.

The object, temporarily known as A/2017 U1, was discovered Oct. 19 by Institute for Astronomy postdoctoral researcher Rob Weryk as he searched for near-Earth objects for NASA using a Pan-STARRS 1 telescope pointed over the volcano Haleakala.

"It was definitely very odd," Weryk told West Hawaii Today of the fast-moving near-Earth object, which was moving so fast that he thought it was closer to Earth than it really was. It didn't resemble other asteroids or comets, and astronomers aren’t at all sure that it was either.

"Its motion could not be explained either using the normal solar system asteroid or comet orbit," Weryk said in the news release.

David Farnocchia, a scientist at CENOS, said the object maintained "the most extreme orbit" he has ever seen.

"It is going extremely fast and on such a trajectory that we can say with confidence that this object is on its way out of the solar system and not coming back," he said in the release.

The object came so close to the sun that it should have burned up, but didn't, suggesting that it may have been a comet or asteroid. It was fairly small, about 500 feet in diameter, but it could have damaged any celestial body it crossed paths with as it plunged toward the sun. Fortunately, it did not have any close encounters with the eight major planets in our solar system.

The Institute for Astronomy said the object approached our solar system from almost directly "above" the ecliptic, the plane in space near where the planets and most asteroids orbit the sun. On Sept. 2, the small body crossed under the ecliptic just inside of Mercury's orbit and then made its closest approach to the sun on Sept. 9. Pulled by the Sun's gravity, the object made a hairpin turn under our solar system, passing below Earth's orbit on Oct. 14, and has now shot back up above the plane of the planets and, traveling at 27 miles per second, is now zooming toward the constellation Pegasus.

• Taurids Meteor Shower Fireballs: Peak Dates, What to Expect
• Two Neutron Stars Collide, And The Result Is Pure Gold

Photo: An infrared image of 41 distant galaxy clusters captured by the Hubble Space Telescope via NASA