'Farfarout' is officially the most distant object in our solar system
Farfarout now has an official designation: 2018 AG37.
It's official: Farfarout is our solar system's most distant known object.
The planetoid dubbed Farfarout was first detected in 2018, at an estimated distance of 140 astronomical units (AU) from the sun — farther away than any object had ever been observed. (One AU is the average Earth-sun distance — about 93 million miles, or 150 million kilometers. For perspective, Pluto orbits at an average distance of about 39 AU.)
Farfarout's inherent brightness suggests a world roughly 250 miles (400 kilometers) wide, barely enough to qualify for dwarf planet status. But the size estimate assumes the world is largely made of ice, and that assumption could change with more observations.
That designation, announced Wednesday (Feb. 10) in a Minor Planet Center electronic circular, is 2018 AG37. (Farfarout will also receive a catchier official moniker down the road.)
"A single orbit of Farfarout around the sun takes a millennium," discovery team member David Tholen, an astronomer at the University of Hawai'i, said in a university statement. "Because of this long orbital period, it moves very slowly across the sky, requiring several years of observations to precisely determine its trajectory."
"Farfarout was likely thrown into the outer solar system by getting too close to Neptune in the distant past. Farfarout will likely interact with Neptune again in the future, since their orbits still intersect," Chad Trujillo, an exoplanet astronomer at Northern Arizona University, said in a statement from the National Science Foundation's NOIRLab. (The laboratory's name reflects an acronym no longer used by NSF.)
The team that spotted Farfarout is well known for peering deep into the dark and frigid outer solar system. For example, in 2018, the researchers also found the distant object Farout and a faraway dwarf planet nicknamed "The Goblin."
And just to be clear: Farfarout's distance record refers to its current location. There are a number of other objects, such as the dwarf planet Sedna, whose orbits take them much farther away from the sun at points than Farfarout will ever get. And scientists think there are trillions of comets in our solar system's Oort Cloud, which begins about 5,000 AU from the sun.
