“Far Out,” Man — Astronomers Discover Most Distant Body In The Solar System

Artist concept of 2018 VG18 “Farout”. Roberto Molar Candanosa/Carnegie Institution for Science

And yes, it’s nicknamed “Farout.” On Monday, Dec. 17, astronomers Scott Sheppard (Carnegie), David Tholen (Univ. of Hawaii) and Chad Trujillo (N. Arizona Univ.) announced the discovery of a new asteroid with the temporary name of 2018 VG. It’s the first solar system object that’s been detected at a distance of 100 times farther than Earth is from the sun. One Earth-sun distance is known as an “astronomical unit” or AU — Farout’s actual distance at the moment is about 120 AUs, which is more than 3.5 times as remote as the dwarf planet Pluto. Baby, it’s cold out there!

Movie using the two discovery images of 2018 VG18 “Farout” taken an hour apart. The object is located in the constellation Taurus. Scott S. Sheppard/David Tholen

2018 VG18 was discovered during the team’s search for extremely distant solar system bodies, including the suspected Planet X, also known as Planet 9. You might remember the team’s discovery of 2015 TG387, nicknamed “The Goblin,” this past October because it was found around Halloween. The Goblin and another remote asteroid, 2012 VP113, have orbits that appear to be influenced by a yet-to-be-found super-Earth-sized planet even further out. The team doesn’t know 2018 VG18’s orbit very well yet, so they haven’t been able to determine if its movements may also by affected by a putative Planet 9.

“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,” said Sheppard in a press release. “ On the plus side, it was found in a similar part of the as the other “extremist” planetoids. All we know for sure about this speck of light is its distance from the sun, brightness, diameter and color. It’s estimated that it takes more than 1,000 years for it to make one orbit around the sun. Pluto completes a round every 248 years. A distant object moves so slowly that it takes many observations over months or even years to fathom even a skinny segment of its travels, and from there to calculate an orbit.

Solar System distances to scale showing the newly discovered 2018 VG18 “Farout” compared to other known solar system objects. Roberto Molar Candanosa/Scott S. Sheppard/Carnegie Institution for Science

Farout’s brightness suggest it’s about 310 miles (500 km) in diameter, big enough for its self-gravity to have crushed it into a spherical shape. And it’s pinkish, a color often associated with icy planets and asteroids. Methane ice (methane freezes out at –297° F / –183° C) reacts with ultraviolet light in sunlight to form pink or red compounds.

“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,” said Trujillo.

You may have read about the Kuiper Belt, a second belt of icy asteroids starting just beyond the orbit of Neptune and extending to around 50 AU. There may be as many as 100 millions objects here 12 miles (20 km) and smaller. Farout’s home lies far beyond even that remote redoubt, in the Scattered Disk, so named because the objects are thought to have been booted there by the outer planets, principally Neptune. There are fewer than 300 scattered disk objects known but given the immense volume of space at that distance, there must be millions more waiting to be discovered.