2026 ED138 is a large, icy object beyond Pluto that the NSF–DOE Vera C. Rubin Observatory announced on October 27, 2026, as its first dwarf planet candidate.
Matthew Holman of the Center for Astrophysics | Harvard & Smithsonian spotted it on October 13 while running Rubin data through a search code he built with Kevin Napier. Rubin’s Simonyi Survey Telescope had observed it 30 times on 20 nights between March 4 and July 11, 2026, and older Dark Energy Camera images trace its orbit back to 2016. It is about 46 astronomical units from the Sun, compared with Pluto’s average of 40, and its orbit is tilted almost 25 degrees. Based on its brightness and distance, the team estimates it is 600 to 1,500 kilometers across, large enough that it should be round. Infrared observations are still needed to confirm that. If confirmed, it would join Pluto, Ceres, Eris, Haumea and Makemake as the sixth dwarf planet recognized by the International Astronomical Union. It likely went unnoticed because it sits near the crowded plane of the Milky Way.
Image: Orbit of 2026 ED138 with the known dwarf planets. NSF–DOE Vera C. Rubin Observatory/NOIRLab/SLAC/AURA/R. Proctor, CC BY 4.0, via NOIRLab.