Farout! Astronomers find farthest known solar system object
Monday, December 17, 2018, 9:11 PM - Newly discovered dwarf planet 2018 VG18, nicknamed "Farout" by the astronomers that found it, is now the farthest known solar system object ever found!
Astronomers sweeping the outer reaches of our solar system still haven't found Planet X, but they have been turning up some amazing discoveries - a dozen previously unknown moons of Jupiter, and a distant object they called The Goblin (due to being found near Halloween.
Their latest discovery is a new record-breaker, though!
On November 10, 2018, images captured by astronomers Scott S. Sheppard, from the Carnegie Institution for Science, and David Tholen, from the University of Hawaii, using the Subaru Telescope atop Hawaii's Mauna Kea volcano, were found to have an object that was moving against the backdrop of stars.
This animation is composed of the two 'discovery images' of 2018 VG18 "Farout", taken an hour apart from the Subaru Telescope, on November 10, 2018. Farout is the small object in the centre, that moves between the two frames, whereas all of the other stationary objects are distant stars and galaxies. Credit: Scott S. Sheppard/David Tholen.
Recorded in the catalogue of solar system objects as '2018 VG18', based on the timing of its discovery, the astronomers who spotted it ended up giving it a nickname - 'Farout'.
Why? As they observed it further, with more images of it captured by Northern Arizona University graduate student Will Oldroyd in early December, using the Magellan telescope at the Las Campanas Observatory in Chile, they found that it was the most distant known object in the solar system!
Farout is at a distance of around 120 astronomical units from the Sun, or 120 times farther than the distance from the Sun to the Earth. For comparison, Pluto is roughly 34 astronomical units (or AU) from the Sun, and Eris, the previous 'farthest known object in the solar system' is 96 AU from the Sun. 120 AU is also the current distance of the Voyager 2 spacecraft, which just left the heliosphere, to enter interstellar space!
Solar System distances to scale showing the newly discovered 2018 VG18 "Farout" compared to other known Solar System objects. Credit: Roberto Molar Candanosa/Scott S. Sheppard/Carnegie Institution for Science.
All that's known about Farout, at the moment, is its distance (120 AU), its size (around 500km across), and its colour (pink!).
According to the Carnegie Science press release, the pink colour of Farout is due to the icy nature of the object.
The combination of water ice, methane ice and carbon dioxide ice in these distant objects, reacting with solar radiation, even at those far distances, is apparently the source of this pink colour.
The question now about Farout, in its position way out in the solar system, is: Does it behave like the other distant solar system objects, which is to say, does 2018 VG18 have a far elliptical orbit, that points to the existence of a hypothetical Planet X.
The orbits of several known outer solar system objects, shown skewed to the left of the above image, reveal the possible existence of a larger planet (perhaps a super-Earth) with an orbit on the other side of the solar system. Credit: Wikimedia Commons
"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 Scott S. Sheppard, of the Carnegie Institution for Science, who is one of the three astronomers credited with the discovery. "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."
It may be years from now, before we can find out if Farout's orbit supports the idea of Planet X being out in the distant reaches of the solar system, but based on the rate that we are discovering these new objects, chances are we'll have an entire crop of them to observe soon, and these astronomers (Scott S. Sheppard, specifically, as he is focused on this target), may actually spot Planet X, itself!
Sources: Carnegie Institution for Science