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Vera Rubin Observatory spots candidate dwarf planet beyond Neptune
Space.com reports that astronomers using Vera Rubin Observatory data found 2026 ED138, an icy body that may be large enough to qualify as a sixth dwarf planet if its size is confirmed.
Astronomers using data from the Vera C. Rubin Observatory in Chile have identified an icy body beyond Neptune that may be large enough to count as a dwarf planet, Space.com reported, citing a discovery announced Tuesday1.
The object, designated 2026 ED138, is estimated at about 600 to 1,500 kilometers (373 to 972 miles) across, a range that could put it above the size needed for gravity to pull it into a roughly spherical shape, a criterion used to distinguish dwarf planets from smaller rocks1.
Matthew Holman of the Center for Astrophysics | Harvard & Smithsonian found the body on Oct. 13 while running archived Rubin images through search software he developed with colleague Kevin Napier1. Despite its great distance from the sun, the object appeared relatively bright, suggesting it is larger than a typical trans-Neptunian body1.
Holman said in a statement quoted by Space.com that his first reaction was "excited disbelief" and that he checked whether he or the code had erred1. He and Mario Juric of the University of Washington, Rubin’s solar system lead scientist, later found that Rubin had imaged 2026 ED138 30 times on 20 nights between March 4 and July 11, 20261.
Astronomers have confirmed five dwarf planets: Pluto, Ceres, Eris, Haumea and Makemake1. Space.com reported that whether 2026 ED138 joins that list depends on a firmer size measurement, which would require infrared observations of the kind NASA’s James Webb Space Telescope is designed to make1.
The observatory, on Cerro Pachon in northern Chile, began its 10-year Legacy Survey of Space and Time after first light in April 2025, Space.com said1. Holman said Rubin will repeatedly image the southern sky, bringing other distant worlds within reach if they exist in regions earlier surveys missed1.
