Move over, FarOut, and make way for FarFarOut.
FarOut was dubbed the most distant known object in our solar system in December. It was the first object found more than 100 times farther than Earth is from the sun.
The distance between the Earth and the sun is an astronomical unit or AU, 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. By comparison, Pluto is 34 AU away.
FarFarOut is 140 AU from the sun. It was discovered February 20 by Scott Sheppard, staff scientist in the Department of Terrestrial Magnetism at the Carnegie Institution for Science.
On that day, he was going to give a lecture called “Beyond Pluto: The Hunt for a Massive Planet X,” but it was delayed until the next day because of inclement weather. He had nothing to do, so he went looking through his team’s data. And that’s where he found FarFarOut.
“This is hot off the presses,” Sheppard said during his lecture on Thursday. “It’s very faint, on the edge of our ability to detect it. It was just discovered in our data from last month.”
Based on its distance and brightness, it is probably about 400 kilometers in size and probably a dwarf planet-size object, Sheppard said. More observations will be needed to determine the orbit.
Researchers don’t know anything else about the object, but Sheppard and his team are hoping to observe it again with the Magellan telescope this week.
“We need to reobserve the object again to confirm it is far far out there,” Sheppard wrote in an email. “Right now we only have observed Farfarout for a 24 hour time base. These discovery observations show Farfarout is around 140 AU, but it could be somewhere between 130 and 150 AU as well.”
Sheppard and his team are still in the process of observing FarOut as well and don’t know its orbit, either. This process could take a year or two of observations to figure out, he said.
They believe that FarOut 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 object was found by 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. Followup observations with Carnegie’s Las Campanas Observatory’s Magellan telescope in Chile determined its path, brightness and color.
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.