Rubin Observatory finds its first dwarf-planet candidate: 2026 ED138 beyond Neptune

Astronomers have found the first dwarf-planet candidate in Vera C. Rubin Observatory data, an object designated 2026 ED138, Space.com reports. It was discovered on October 13 by Matthew Holman of the Center for Astrophysics | Harvard & Smithsonian, with Mario Jurić helping confirm it.

Rubin recorded the object 30 times on 20 nights between March 4 and July 11, 2026, and older Dark Energy Camera images go back to 2016. Its estimated diameter is 600 to 1,500 kilometres; it lies about 46 astronomical units from the Sun on an orbit tilted about 25 degrees.

What comes next

Infrared measurements from the James Webb telescope are needed to pin down its size. If it proves large and round enough, it would become the sixth officially recognised dwarf planet, alongside Pluto, Eris, Haumea, Makemake and Ceres.