A New Giant in the Kuiper Belt
Astronomers have identified a potential new dwarf planet orbiting the sun in the distant Kuiper Belt, roughly 46 times farther from the sun than Earth is. Designated 2026 ED138, researchers estimate the object has a diameter between 600 and 1500 kilometers.
Discovery at the Vera C. Rubin Observatory
The celestial body was spotted using the Vera C. Rubin Observatory, located on the peak of Cerro Pachón in Chile. Details of the finding were shared at a meeting of the American Astronomical Society.
Astrophysicist Matt Holman at the Center for Astrophysics in Cambridge first spotted the candidate object in data compiled from multiple exposures taken between March 4 and July 11, 2026. The object stands as the largest among 2,300 new objects discovered beyond Pluto. Mario Juric, who leads solar system research at the Rubin Observatory, presented the findings to the American Astronomical Society.
Holman explained that the telescope captures sunlight reflected from objects, noting that observing at longer wavelengths helps astronomers determine the actual size of distant bodies rather than relying solely on surface reflectivity.
The Path to Official Classification
Further observations are required to determine whether 2026 ED138 meets the formal definition of a dwarf planet. The International Astronomical Union has established three specific criteria: the object must orbit the sun, possess sufficient mass for its own gravity to pull it into a near-spherical shape, and fail to clear its orbital path of other debris.
Expanding the Edge of the Solar System
If approved, it will join Ceres, Eris, Haumea, Makemake, and Pluto as the sixth known dwarf planet in the solar system.
The discovery offers fresh insight into the outermost boundaries of the solar system, where the sun’s gravitational reach extends far beyond the planets. Paul Byrne, an astronomy professor at Washington University in St. Louis, described the finding as deeply exciting, noting that each discovery brings researchers closer to understanding how planetary systems formed. The object shares characteristics with Pluto, residing in an expanse where conditions remain largely unaltered since the birth of the solar system, which was reclassified from its status as the ninth major planet in 2006.
