BEYOND NEPTUNE
Large Object Found Lurking Past Pluto; Astronomers Weigh Dwarf Planet Claim
Provisionally named 2026 ED138, the body was spotted in Rubin Observatory data and may span anywhere from 600 to 1,500 kilometers, according to its discoverers.
SPOKANE, WASH. — Astronomers have announced the discovery of a distant object, provisionally designated 2026 ED138, that may qualify as a dwarf planet, according to a report in The Debrief. The find was made in data from the NSF–DOE Vera C. Rubin Observatory.
Matthew Holman of the Center for Astrophysics, Harvard & Smithsonian, identified the object on October 13 while analyzing observations gathered earlier this year. Its brightness and distance suggested a body of considerable size, estimated at between 600 and 1,500 kilometers across, though the report stresses that further observations are needed to pin down its dimensions.
Holman and Mario Jurić, a University of Washington astronomy professor and Rubin's solar system lead scientist, presented the findings at a press conference during the 58th annual Division for Planetary Sciences meeting in Spokane. Jurić called the object the largest trans-Neptunian object found in about 20 years, and said such a discovery happens roughly once in a generation.
The object sits about 46 astronomical units from the Sun, against Pluto's 40, according to the report. If confirmed, it would join Pluto, Ceres, Eris, Haumea and Makemake among the dwarf planets recognized by the International Astronomical Union. That definition requires a body to orbit the Sun, be massive enough to pull itself into a nearly round shape, and not have cleared its orbital neighborhood.
Holman located the object with software developed with fellow astrophysicist Kevin Napier, which sifts billions of detections to link sightings of the same moving body. Jurić then searched archival images and turned up 20 more, reaching back to March 2026. In all, Rubin's Simonyi Survey Telescope recorded the object 30 times over 20 nights between March 4 and July 11.
Holman described his first reaction as "excited disbelief," and said he checked whether he or the code had erred. He added that Rubin's decade-long survey of the southern sky may reveal others hiding in places earlier surveys skipped.