Scientists using the NSF–DOE Vera C. Rubin Observatory in Chile have identified a large icy body beyond Pluto, provisionally designated 2026 ED138, that they describe as a dwarf-planet candidate^2,3.

The University of Washington said it sits about 46 astronomical units from the sun, compared with Pluto’s average of about 40 au, making it a trans-Neptunian object³. NSF said the IAU Minor Planet Center issued the provisional designation ED138².

Matthew Holman of the Center for Astrophysics | Harvard & Smithsonian first flagged the candidate, and Mario Jurić of the University of Washington, who leads Rubin’s solar-system team, added observations, UW said³. Results were presented at a press conference, UW said³.

UW said Holman noticed that the object’s brightness and distance implied an unusually large body³. Based on distance, brightness and assumed surface reflectivity, UW put the diameter between 600 and 1,500 kilometers, a range in which icy worlds are expected to be round, though it said further observations are needed to confirm a dwarf-planet classification³.

NSF said if confirmed the object would join the five known dwarf planets: Pluto, Ceres, Eris, Haumea and Makemake². UW said the same five are recognized by the International Astronomical Union³.

NSF said the object was found near the crowded plane of the Milky Way, which likely delayed discovery, and that Rubin’s repeated scans and algorithms made the motion stand out².

Jurić said finding an object this big, roughly 1,000 kilometers across, is something that happens maybe once in a generation³. NSF quoted DOE program manager Kathy Turner as saying Rubin’s strengths apply from dark energy to this dwarf-planet candidate².

NSF and UW said other observatories can now follow up^2,3.