The farthest known object in the Solar System is now confirmed. FarFarOut, a large piece of stone found in 2018 at an enormous distance of about 132 astronomical units from the Sun, has been studied and characterized, and now we know much more about it and its orbit.
It has a distance of about 400 kilometers, which is at the lower end of the dwarf planet’s scale, and initial observations suggest that it has an average orbital distance of 101 astronomical units – 101 times the distance between Earth and Sun.
Because Pluto has an average orbital distance of about 39 astronomical units, FarFarOut is very, well, far away. It received the provisional name 2018 AG37, and its proper name, according to the guidelines of the International Astronomical Union, is still pending.
That orbit, however, is not an equal circle around the Sun, but a truly lopsid oval. After careful observation, the scientists calculated their orbit; FarFarOut moves up to 175 astronomical units and is approaching 27 astronomical units, inside the orbit of Neptune.
(Roberto Molar Candanosa, Scott S. Sheppard / CSI and Brooks Bays / UH)
This means that the object could help us better understand the planets of the outer solar system.
“FarFarOut was probably thrown into the outer solar system because it was too close to Neptune in the distant past,” said astronomer Chad Trujillo of the University of Northern Arizona. “FarFarOut will likely interact with Neptune again in the future, as their orbits still intersect.”
The nickname of the object has evolved since the discovery of a previously distant object in 2018.
The artist’s impression of FarFarOut. (NOIRLab / NSF / AURA / J. da Silva)
The dwarf planet Farout has an average orbital distance of 124 astronomical units and was named after an exclamation made by astronomer Scott Sheppard of the Carnegie Institution for Science. When he and his team discovered an even more distant object, progress was evident.
However, FarFarOut is still very mysterious. Because it is so far away, it is extremely weak and has only been observed nine times in two years. The team deduced its size based on its brightness, but we don’t know much; it could be a very large irregular object in the Kuiper Belt or it could meet the criteria to be classified as a dwarf planet.
FarFarOut discovery images obtained in July 2018. (Scott S. Sheppard / Carnegie Institution for Science)
Also, astronomers are not entirely sure of its orbit time. They think he might just be shy for 800 years (Pluto’s is 248), but there’s enough room for it to last more than twice, or move at a much faster pace.
Therefore, many more observations will have to be made to better understand it.
“FarFarOut takes a millennium to orbit the Sun once,” said astronomer David Tholen of the University of Hawaii at Manoa. “Because of this, it moves very slowly in the sky, requiring several years of observations to accurately determine its trajectory.”
Sheppard, Tholen, and Trujillo are working on studying the outer solar system in hopes of gaining a glimpse of the New Planet, a hypothetical object believed to be responsible for the strange movement of groups of objects outside beyond Pluto.
There are other explanations for these orbits, but the work has an excellent secondary advantage. The team discovered a number of objects we did not know about. There are, of course, Farout and FarFarOut. There is also a dwarf planet nicknamed Goblin, discovered at a distance of 80 astronomical units.
There is even an object, called 2014 FE72, whose orbit takes it beyond 3,000 astronomical units, the only known object of its kind with an orbit entirely outside of Neptune. (It is now much closer after its close proximity to the Sun in 1965.)
Nor is it just the outer solar system. The researchers discovered 12 previously unknown months in orbit around Jupiter and 20 months orbiting Saturn.
So if there is a New Planet there, they seem to be the people who will find it. But in the process, it reveals a lot about the outer solar system.
“The discovery of FarFarOut shows our growing ability to map the outer solar system and look farther and farther to the edges of our solar system,” said Sheppard.
“Only with the progress made in recent years in large digital cameras on very large telescopes has it been possible to efficiently discover very distant objects such as FarFarOut. Even though some of these distant objects are quite large – the size of dwarf planets – they are very weak due to their extreme distances from the Sun. FarFarOut is just the tip of the iceberg of objects in the very distant solar system. “