Vera Rubin Observatory Spots Its First Dwarf Planet Candidate Beyond Pluto
Before its decade-long survey has even officially begun, the Vera Rubin Observatory has identified a dwarf planet candidate called 2026 ED138 beyond Neptune, estimated at up to 1,500 km wide — potentially one of the largest such objects ever found.
The NSF–DOE Vera C. Rubin Observatory has revealed its first dwarf planet candidate, a trans-Neptunian object designated 2026 ED138, before its primary decade-long Legacy Survey of Space and Time officially commenced. Astrophysicist Matthew Holman of the Center for Astrophysics at Harvard & Smithsonian discovered the object on October 13, 2026, while running early Rubin data through a search algorithm. Holman works on the algorithms that guide Rubin's search for transient objects in the night sky. The object lies roughly 46 astronomical units from the Sun — slightly farther out than Pluto's average distance of 40 AU — and has an orbital inclination of about 25 degrees. Based on its brightness and estimated surface reflectivity, scientists calculate its diameter to be between 600 and 1,500 kilometres, which would make it potentially one of the largest dwarf planets known beyond Neptune if confirmed. The observatory observed it 30 times across 20 separate nights between March and July 2026, and archival images from the Dark Energy Camera trace its orbit back to 2016. Confirmation of its dwarf planet status requires further observations. The discovery showcases the observatory's power to detect faint, distant objects through repeated imaging and advanced algorithms, and hints at the thousands of objects it is expected to uncover during its full operational decade.
