Astronomers at Harvard have found what they believe is a previously undiscovered dwarf planet in our own solar system. The object, provisionally called 2026 ED138, orbits beyond Pluto.
The discovery was announced on Tuesday at the 59th Annual Division for Planetary Sciences meeting of the American Astronomical Society in Spokane, Washington. Matthew Holman, a Smithsonian astrophysicist and lecturer at Harvard University, presented the results with Mario Juric, a University of Washington professor of astronomy.
Scientists estimate the object is between 600 and 1,500 kilometres across, which would place it among the largest bodies found in the outer solar system. Holman said researchers do not yet know its exact size because they can only measure how much light it reflects, so it could be a smaller, brighter object or a larger, darker one.
The object stayed hidden because it sits in one of the brightest parts of the night sky, the Milky Way. Holman spotted it by running data from the Vera C. Rubin Observatory through a search code, then confirmed it with more than 30 Rubin observations from March to July 2026 and archival sightings going back to 2016.
If confirmed, 2026 ED138 would join the five dwarf planets recognised by the International Astronomical Union: Pluto, Ceres, Eris, Haumea and Makemake. Further observations will determine whether its own gravity has pulled it into a round shape, the key test for dwarf planet status.
Source: Phys.org
