Astronomers identify distant object that could qualify as a dwarf planet
The object, provisionally named 2026 ED138, could be 600 to 1,500 kilometers across, but further observations are needed to establish its size and status.
Astronomers have identified a distant icy object in observations from the NSF-DOE Vera C. Rubin Observatory that could become the solar system's sixth officially recognized dwarf planet. Provisionally named 2026 ED138, it is approximately 46 astronomical units (au) from the Sun.
Matthew Holman, a senior astrophysicist at the Harvard & Smithsonian Center for Astrophysics, spotted the object on October 13 while reviewing data collected earlier in 2026. He used software developed with colleague Kevin Napier to identify moving objects among billions of telescope detections.
Mario Jurić, a University of Washington astronomy professor leading Rubin's solar system team, subsequently found 20 more detections in the observatory's records, some from March 2026. Searches of other surveys uncovered images dating to 2016, helping the researchers reconstruct the object's orbit.
Astronomers estimate a diameter of 600 to 1,500 kilometers using its brightness, distance and assumptions about its surface reflectivity. That range could give an icy body enough gravity to become nearly round, an essential condition for dwarf planet status. Further observations are needed to determine its dimensions and whether it qualifies.
ED138 appears near the Milky Way's plane, where a dense background of stars made its movement difficult for earlier searches to detect. Rubin's repeated observations and computer processing helped distinguish it. The International Astronomical Union currently recognizes five dwarf planets: Pluto, Ceres, Eris, Haumea and Makemake.
