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'Farout,' the most-distant solar system object discovered

Team had been searching for planet since 2014
Posted at 11:38 AM, Dec 17, 2018

For the first time, an object in our solar system has been found more than 100 times farther than Earth is from the sun.

The International Astronomical Union's Minor Planet Center announced the discovery Monday, calling the object 2018 VG18. But the researchers who found it are calling it "Farout."

They believe the spherical object is a dwarf planet more than 310 miles in diameter, with a pinkish hue. That color has been associated with objects that are rich in ice, and given its distance from the sun, that isn't hard to believe. Its slow orbit probably takes more than 1,000 years to make one trip around the sun, the researchers said.

The distance between the Earth and the sun is an AU, or astronomical unit -- the equivalent of about 93 million miles. Farout is 120 AU from the sun. Eris, the next most distant object known, is 96 AU from the sun. For reference, Pluto is 34 AU away.

The object was found by the Carnegie Institution for Science's Scott S. Sheppard, the University of Hawaii's David Tholen and Northern Arizona University's Chad Trujillo -- and it's not their first discovery.

The team has been searching for a super-Earth-size planet on the edge of our solar system, known as Planet Nine or Planet X, since 2014. They first suggested the existence of this possible planet in 2014 after finding "Biden" at 84 AU. Along the way, they have discovered more distant solar system objects suggesting that the gravity of something massive is influencing their orbit.

Farout was found using the Japanese Subaru 8-meter telescope on Hawaii's Mauna Kea in November. Follow-up observations with Carnegie's Las Campanas Observatory's Magellan telescope in Chile determined its path, brightness and color.

"This discovery is truly an international achievement in research using telescopes located in Hawaii and Chile, operated by Japan, as well as by a consortium of research institutions and universities in the United States," Trujillo said in a statement. "With new wide-field digital cameras on some of the world's largest telescopes, we are finally exploring our Solar System's fringes, far beyond Pluto."

In October, the team announced the discovery of "the Goblin" at 80 AU; it's so named because the distant solar system object was first spotted near Halloween.

It's unlikely that these objects are influenced by the gravity of gas giants Neptune and Uranus because they never get close enough to them -- which indicates that something else is determining their orbits.

Farout's orbit is yet to be determined.

"2018 VG18 is much more distant and slower moving than any other observed Solar System object, so it will take a few years to fully determine its orbit," Sheppard said in a statement. "But it was found in a similar location on the sky to the other known extreme Solar System objects, suggesting it might have the same type of orbit that most of them do. The orbital similarities shown by many of the known small, distant Solar System bodies was the catalyst for our original assertion that there is a distant, massive planet at several hundred AU shepherding these smaller objects."