is a large trans-Neptunian object and possible dwarf planet orbiting in the scattered disc of the outermost regions of the Solar System, estimated to be around () in diameter. , it is approximately from the Sun, and will slowly decrease in distance until it reaches its perihelion of 38 AU in 2142. The discoverers have nicknamed it "DeeDee" for "Distant Dwarf".
was discovered by a team led by David Gerdes using data collected by the large camera Dark Energy Camera (DECam). The discovery was announced by the Minor Planet Center on 11 October 2016. Assuming its nominal diameter of , it reflects just 13 percent of the sunlight that hits it. The earliest known precovery observations of were taken at the Mauna Kea Observatory on 15 October 2006.
has not yet been imaged by high-resolution telescopes, so it has no known moons. The Hubble Space Telescope is planned to image in 2026, which should determine if it has any significantly sized moons.
Orbit
orbits the Sun once every approximately 1,150 years and at the current point in its orbit is the second farthest known object from the Sun with a stable orbit. Its perihelion is calculated to be a bit closer than Pluto's semi-major axis, and it is calculated to reach it in 2142.
Orbital stability Gerdes et al. simulated clones of the orbit of for 1 billion years (1 Gyr). It remains close to its orbit over the time of the simulations and does not undergo libration, even with the potentially destabilizing interactions with Neptune, and being in possibly a 7:1 mean-motion resonance with Neptune. They also performed several simulations of the entire 4.5 Gyr history of the solar system, and remained stable.
In a 2021 study by Muñoz-Gutiérrez et al. analyzed and simulated the orbit of over a period of 1 Gyr. they simulated that ’s orbital stability is unstable over a time scale of 1 Gyr, however they calculate a diffusion time of 55.069 Gyr, making it very stable.
Physical characteristics Diameter, mass and albedo has a measured diameter of , using thermal measurements from the Atacama Large Millimeter Array in the Atacama Desert of northern Chile. They assume a spherical body, and a uniform surface for this diameter.
has no measured mass, due to it not having a known moon as of 2026. however Muñoz-Gutiérrez et al. estimates a mass of . Interior Gerdes et al. states that is likely a dwarf planet with a mixed ice-rock composition.
However, a planetary study by William M. Grundy suggests that trans-Neptunian objects in the 400–1000 km size range form a transition zone between small, low-density bodies and large, dense dwarf planets. Since has an diameter of , it falls in this transition zone.
Surface and spectra has color indices of: g-r of ; r-i of ; i-z of . With also a geometric albedo of . Using the diameter of , they assume a uniform surface for the diameter.
Numbering and naming
As of 2025, has not been numbered by the Minor Planet Center, as the uncertainty of its orbit is still large. The discoverers will have sole right to propose a name for ten years from the date it is numbered.
See also List of Solar System objects most distant from the Sun
References (K14UM4Z)
External links 2014 UZ224 ("DeeDee") Fact Sheet