RUBIN OBSERVATORY IDENTIFIES DWARF PLANET CANDIDATE BEYOND PLUTO

Scientists using the NSF–DOE Vera C. Rubin Observatory have identified a possible dwarf planet orbiting beyond Pluto, the observatory said. The International Astronomical Union’s Minor Planet Centre gave the object the provisional designation 2026 ED138. Mario Jurić, a University of Washington astronomy professor, estimated that it measures roughly 1,000 kilometres across. Scientists have yet to confirm its status as a dwarf planet. If confirmed, ED138 would join Pluto, Ceres, Eris, Haumea and Makemake on the International Astronomical Union’s list.

Matthew Holman, an astrophysicist at the Harvard & Smithsonian Centre for Astrophysics, found ED138 on 13 October while examining Rubin data collected earlier in 2026. He used search code developed with Kevin Napier to match detections of moving objects among billions of observations. Jurić subsequently found 20 more observations in Rubin’s records dating back to March 2026. The observatory said ED138 appeared near the plane of the Milky Way, where millions of stars fill the view. It said that crowded field may explain why earlier searches had missed the object.

The US National Science Foundation and the US Department of Energy’s Office of Science jointly fund Rubin Observatory. Its Simonyi Survey Telescope uses a camera that the observatory describes as the largest ever built. “It’s the largest trans-Neptunian object found in about 20 years, and Rubin turned it up while we were still commissioning the telescope,” Jurić said. The observatory said scientists could use other telescopes to make further observations of ED138 and investigate its nature. Members of the public can explore the discovery through Orbitviewer, an interactive solar system app.