An
international team of astronomers has discovered the furthest object ever
detected in the Solar System. Nicknamed “Farout”, it’s a small round object
with a pinkish hue located 17.95 billion kilometers (11.15 billion miles) from
the Sun. The color is common in ice-rich objects.
Its official
designation is 2018 VG18 and it is 500 kilometers (310 miles) in diameter. It's
the first object discovered further than 100 astronomical units (AU) from our
star, with 1 AU being the Earth-Sun distance. Farout is at a distance of 120
AU, significantly further out than dwarf planet Eris, which is at 96 AU. Pluto,
by comparison, is at 34 AU.
The object
was discovered in images taken with the Japanese Subaru Telescope atop Mauna
Kea in Hawaii on November 10. Follow-up observations to confirm the distance
were conducted in December from Las Campanas Observatory in Chile.
“All that we currently know about 2018 VG18 is its extreme distance from the Sun, its approximate diameter, and its color,” co-discoverer David Tholen, from the University of Hawaii, said in a statement. “Because 2018 VG18 is so distant, it orbits very slowly, likely taking more than 1,000 years to take one trip around the Sun.”
Farout adds
to the intriguing family of peculiar objects so far discovered beyond the orbit
of Pluto. The orbits of these trans-Neptunian objects (TNOs) seem to be
influenced by the gravity of a massive planet so researchers have put forward
the idea that Planet 9 exists over 200 AU from the Sun. So far the search
hasn’t uncovered definitive proof, but TNOs are helping astronomers understand
what’s going on at the edge of the Solar System.
“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,” added
co-discoverer Scott Sheppard, from the Carnegie Institution for Science. “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.”
While we are
only just starting to understand the further rims of the Solar System,
discoveries like this show that there are still many worlds out there left to
find.
Solar System
distances to scale showing the newly discovered 2018 VG18 compared to other
Solar System objects. Roberto Molar Candanosa/Scott S. Sheppard/Carnegie
Institution for Science.
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