Carnegie Institution astronomer Dr. Scott S. Sheppard, University of Hawaii’s Dr. David Tholen and Northern Arizona University’s Dr. Chad Trujillo have discovered the most-distant body ever observed in the Solar System — a dwarf planet named 2018 VG18.
An artist’s concept of 2018 VG18. Image credit: Roberto Molar Candanosa / Carnegie Institution for Science.
The discovery images of 2018 VG18, nicknamed ‘Farout,’ were taken at the Subaru Telescope located atop Mauna Kea in Hawaii on November 10, 2018.
The subsequent observations showed that 2018 VG18 is around 120 AU (astronomical units), making it the first solar system object observed beyond 100 AU.
The second-most-distant observed solar system object is Eris, at about 96 AU. Pluto is currently at about 34 AU, making 2018 VG18 more than three-and-a-half times more distant than the Solar System’s most-famous dwarf planet.
2018 VG18 and other known solar system objects. Image credit: Roberto Molar Candanosa / Carnegie Institution for Science.
2018 VG18 was discovered as part of astronomers’ search for extremely distant solar system objects, including the hypothetical Planet Nine.
The scientists don’t know the new object’s orbit very well yet, so they have not been able to determine if it shows signs of being shaped by the suspected planet.
“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,” Dr. Sheppard said.
“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.”
A movie of the discovery images of 2018 VG18 from the Subaru Telescope on November 10, 2018. 2018 VG18 moves between the two discovery images while the background stars and galaxies do not move over the 1 hour between images. Image credit: Scott S. Sheppard / David Tholen.
2018 VG18’s brightness suggests that it is about 311 miles (500 km) in diameter, likely making it spherical in shape and a dwarf planet.
It has a pinkish hue, a color generally associated with ice-rich objects.
“All that we currently know about 2018 VG18 is its extreme distance from the Sun, its approximate diameter, and its color,” Dr. Tholen said.
“Because 2018 VG18 is so distant, it orbits very slowly, likely taking more than 1,000 years to take one trip around the Sun.”
The discovery of 2018 VG18 was announced in the Minor Planet Electronic Circular (MPEC) newsletter issued by the International Astronomical Union’s Minor Planet Center on December 17, 2018.
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S. S. Sheppard et al. 2018 VG18. Minor Planet Electronic Circular # 2018-Y14
