Farfarout

Figure showing the discovery images of Farfarout (2018 AG37) from the Subaru telescope on January 15 and 16, 2018. The distant background stars (round white dots) and galaxies (oval, elongated and extended objects) do not move during the 24 hours between images, but Farfarout, being at 132 AU from the Sun, moves between images as shown by the orange highlighted area. Other things come and go in the two images such as the very bright and streaky high energy cosmic rays that strike the camera detector during the 5 minute long images. There is also a main belt asteroid that streaks by in one of the images just to the left of Farfarout. Credit Scott S. Sheppard/Carnegie Institution for Science.

FarFarOut added to count of dwarf sized planets in distant Solar System


A team that includes Carnegie Institution for Science astronomer Scott S. Sheppard discovered the most distant object ever observed in our Solar System. The object is officially named 2018 AG37 but is nicknamed Farfarout for just how far away from the Sun it is orbiting—about 132 AU, where 1 AU is the distance between the Earth and Sun. At that distance, it takes an entire millennium to orbit the Sun.


Sheppard and his colleagues David Tholen (University of Hawaii) and Chad Trujillo (Northern Arizona University) have been surveying the sky since 2012 to map the Solar System beyond Pluto. FarFarOut joins a set of these planetoid discoveries—including the previous record holder, FarOut (2018 VG18) at 124 AU that was discovered by the same team. However, the team is still on the hunt for “Planet X”—a much larger planet that could be orbiting somewhere just beyond Farfarout.


Like a giant game of connect the dots, each new discovery fills in a bigger picture of our very distant Solar System and points astronomers closer to what may be hidden at the fringes of our Solar System. However, because Neptune strongly interacts with Farfarout as Farfarout’s orbit crosses Neptune’s orbit, Farfarout motion across the sky cannot be used to determine if there is another unknown massive planet out there.


Only objects that stay in the very distant Solar System, well beyond the gravitational effects of Neptune, can be used to probe the very distant Solar System for the signs of another massive planet. These include objects like Sedna, 2012 VP113 (nicknamed Biden) and Leleakuhonua. Although they are currently closer to the Sun at around 80 AU, they never approach Neptune in their orbits around the Sun and thus would be strongly influenced not by Neptune but more by other possible massive objects in the distant solar system, like the possible Planet X.


Said Scott Sheppard in a recent press release, "The discovery of Farfarout shows our increasing ability to map the outer Solar System and observe farther and farther towards the fringes of our Solar System.” He continued, "Only with the advancements in the last few years of large digital cameras on very large telescopes has it been possible to efficiently discover very distant objects like Farfarout. Even though some of these distant objects are quite large, they are very faint because of their extreme distances from the Sun. Farfarout is just the tip of the iceberg of solar system objects in the very distant solar system."


To Learn More About the Discovery of Farfarout, check out the press releases below on the announcement made on February 10, 2021.

National Optical Observatories Announcement of Farfarout.

Subaru Telescope Announcement of Farfarout.

University of Hawaii Press Announcement of Farfarout.


Watch a talk given by Scott S. Sheppard on the survey looking for planets beyond Pluto and Farfarout.