Astronomers Identify Potential New Dwarf Planet 2026 ED138 Beyond Pluto
A trans-Neptunian object named 2026 ED138, discovered by the Vera C. Rubin Observatory, may be one of the largest dwarf-planet candidates found beyond Neptune.
Astronomers announced the discovery of a bright, distant object designated 2026 ED138, which could be classified as a dwarf planet in the outer Solar System. The object was identified in data from the Vera C. Rubin Observatory’s Legacy Survey of Space and Time, a ten-year program that continuously images the southern sky.
The find was made by Rubin Operations team member Matthew Holman of the Center for Astrophysics | Harvard & Smithsonian while analysing observations collected earlier in the year. Using a search algorithm that compares billions of moving-object detections, Holman flagged the object for its unusual brightness and distance, suggesting a size between 600 and 1,500 kilometres.
"My first reaction was one of excited disbelief. Objects like this are very rare, so I immediately started checking whether I or the code had done something wrong," Holman said.
Located about 46 astronomical units from the Sun—roughly six AU farther than Pluto—2026 ED138 follows an orbit tilted about 25 degrees from the ecliptic, classifying it as a “hot-classical” trans-Neptunian object. Its inclined path implies past gravitational interactions with Neptune may have altered its original orbit.
"Rubin Observatory's super power is the ability to clearly capture movement and change among a vast number of objects and phenomena that humans have never seen before," said Edward Ajhar, NSF Program Director for the Rubin Observatory.
The object's position near the dense star fields of the Milky Way’s plane likely contributed to its previous elusiveness, but the Rubin Observatory’s wide-field camera and automated data processing enabled its detection. Astronomers note that infrared observations will be required to confirm the object's size and whether it meets the criteria for dwarf-planet status.
"If confirmed as a dwarf planet, ED138 would join a very small family of worlds," Holman added, noting that the Rubin survey will repeatedly image the southern sky over the next decade, increasing the chances of finding additional distant bodies.