Astronomers have identified a massive icy object lurking 46 astronomical units from the Sun that could become our solar system’s sixth officially recognized dwarf planet.
Holman Spots Candidate Object at Rubin Observatory
The candidate, designated 2026 ED138, was discovered on October 13 by Matthew Holman. Holman was running data collected by the Legacy Survey of Space and Time at the NSF–DOE Vera C. Rubin Observatory through a search code he built with colleague Kevin Napier.
My first reaction was one of excited disbelief,
Holman said, noting that he immediately checked whether he or the code had made an error.
Operations of the Vera C. Rubin Observatory are funded by the U.S. National Science Foundation and the U.S. Department of Energy’s Office of Science. Observations of the object were formally announced on October 27 by the International Astronomical Union’s Minor Planet Center.
The findings were shared at an October 27, 2026 press conference by Matthew Holman alongside Mario Jurić, who heads Rubin’s solar system team and serves as a University of Washington astronomy professor.
Crowded Milky Way Hides Distant Object
The object remained undetected for years because it sits in a crowded stellar field near the plane of the Milky Way. Millions of background stars masked its slow movement across the sky.
Working in his capacity as the University of Washington’s Rubin Solar System Lead Scientist, Mario Jurić uncovered 20 additional observations that raised the sighting count to 30 across 20 distinct nights, tracked by Rubin’s Simonyi Survey Telescope between March 4 and July 11, 2026. The researchers found that this celestial body had been hiding in astronomical archives for a long time, with older observations pushing its track back even further.
And the discovery is just the beginning: Once we identify a new object, we can search back months, and sometimes even decades, finding it in images where nobody knew to look,
Jurić said.
ED138 Orbits Farther from the Sun than Pluto
Preliminary calculations place ED138 roughly 4.3 billion miles from the Sun, farther out than Pluto, which orbits the sun at an average distance of about 3.7 billion miles. ED138 currently sits about 46 astronomical units from the Sun, while Pluto averages around 40.
Astronomers estimate its diameter falls between 373 and 932 miles, or 600 to 1,500 kilometers. Jurić called the find a once-in-a-generation discovery, noting that finding an object roughly 1,000 kilometers across happens maybe once in a generation.
Rubin Observatory’s superpower is the ability to clearly capture movement and change among a vast number of objects and phenomena that humans have never seen before,
Edward Ajhar, NSF program director for Rubin Observatory, said.
Kathy Turner, Department of Energy Program manager for Rubin Observatory, stated that Rubin’s unique strengths make it an incredible tool for investigating a wide range of astrophysical phenomena.
Infrared Observations Will Test Dwarf Planet Status
If confirmed by infrared observations that nail down its exact dimensions and shape, ED138 would join Pluto, Ceres, Eris, Haumea, and Makemake as an officially recognized dwarf planet.
If confirmed as a dwarf planet, ED138 would join a very small family of worlds,
Holman said.
Will infrared observations confirm the exact dimensions and shape of ED138?