JPL Announces 'Visitor' from Another Solar System Will Flyby Earth

Published : Monday, October 30, 2017 | 5:36 AM

Solar System

NASA’s Center for Near-Earth Object Studies (CNEOS) at the Jet Propulsion Laboratory in Pasadena is continuing to track a small recently discovered asteroid – or maybe a comet, as astronomers are still trying to determine what it is – that appears to have originated from outside the solar system, coming from somewhere else in the Milky Way Galaxy. If it indeed came from outside the solar system, it would be the first “interstellar object” to be observed and confirmed by astronomers.

In a JPL press release Thursday, NASA said the object, temporarily designated as A/2017 U1, is about 400 meters in diameter and is moving remarkably fast at 27 miles – about 44 kilometers – per second.

Astronomers are now urgently working to point telescopes around the world and in space at the object, and once data is obtained and analyzed, they may be able to know more about the origin of the object, and possibly what it’s made of.

Researchers at the University of Hawaii’s Pan-STARRS 1 telescope on Haleakala first saw A/2017 U1 on October 19, as they conducted their nightly search for near-Earth objects for NASA. Rob Weryk, a postdoctoral researcher at the University of Hawaii Institute for Astronomy, first identified the moving object and submitted his findings to the Minor Planet Center in Cambridge, Massachusetts.

Weryk subsequently searched the Pan-STARRS image archive and found the object also was in images taken the previous night, although it was not initially identified. He immediately realized it was an unusual object.

“Its motion could not be explained using either a normal solar system asteroid or comet orbit,” Weryk said.

Weryk contacted Institute for Astronomy graduate Marco Micheli, who used his own follow-up images taken at the European Space Agency’s telescope on Tenerife in the Canary Islands, and realized it was an object from outside the solar system.

“This is the most extreme orbit I have ever seen,” said Davide Farnocchia, a scientist at NASA’s Center for Near-Earth Object Studies (CNEOS) at JPL. “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.”

The CNEOS team plotted the object’s current trajectory and even looked into its future. Based on their analysis, A/2017 U1 came from the direction of the constellation Lyra, cruising through interstellar space at a brisk clip of 15.8 miles (25.5 kilometers) per second.

According to NASA’s release, the object approached the solar system from almost directly “above” the ecliptic, the approximate plane in space where the planets and most asteroids orbit the Sun, so it did not have any close encounters with the eight major planets during its plunge toward the Sun.

On September 2, the small body crossed under the ecliptic plane just inside of Mercury’s orbit and then made its closest approach to the Sun on September 9. Pulled by the Sun’s gravity, the object made a hairpin turn under the solar system, passing under Earth’s orbit on October 14 at a distance of about 15 million miles or 24 million kilometers – about 60 times Earth’s distance to the Moon.

The object has now shot back up above the plane of the planets and speeding toward the constellation Pegasus.

At Hawaii’s Institute for Astronomy, astronomer Karen Meech said they have long suspected objects like these exist, as a lot of material could have ejected from planetary systems during the process of planet formation.

“What’s most surprising is that we’ve never seen interstellar objects pass through before,” Meech said.

JPL’s Paul Chodas, who manages CNEOS, said they have been waiting for a chance to see such an object for decades.

“It’s long been theorized that such objects exist – asteroids or comets moving around between the stars and occasionally passing through our solar system – but this is the first such detection,” Chodas said. “So far, everything indicates this is likely an interstellar object, but more data would help to confirm it.”

JPL’s CNEOS, the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) in Hawaii, and the Minor Planet Center are all projects of NASA’s Near-Earth Object Observations Program, and elements of the agency’s Planetary Defense Coordination Office within NASA’s Science Mission Directorate.

For more information about asteroids and near-Earth objects, visit www.cneos.jpl.nasa.gov and
www.jpl.nasa.gov/asteroidwatch.

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