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A new discovery in the outer reaches of the solar system could expand the small group of officially recognized dwarf planets. Scientists working with data from the Vera C. Rubin Observatory identified an unusually large icy object beyond Pluto that may eventually join the list.
Provisionally named 2026 ED138, the object is located in a region beyond Neptune’s orbit. Initial estimates suggest it could measure between 370 and 930 miles in diameter, making it one of the largest potential dwarf planets identified in that distant region.
If additional observations confirm its characteristics, ED138 could become the sixth officially recognized dwarf planet, joining Pluto, Ceres, Eris, Haumea and Makemake. However, researchers have not yet established its exact dimensions or confirmed that it meets the necessary classification criteria.
What scientists know about the object discovered beyond Pluto
ED138 is currently located approximately 46 astronomical units from the Sun. One astronomical unit represents the average distance between Earth and the Sun. By comparison, Pluto orbits at an average distance of around 40 astronomical units.
This makes the newly identified body a trans-Neptunian object, a category that includes celestial bodies orbiting the Sun beyond Neptune.
Its estimated size is particularly significant. To qualify as a dwarf planet, an object must have enough mass for its own gravity to pull it into an approximately spherical shape. Scientists believe ED138 could meet this condition because icy objects of its estimated dimensions are generally expected to become rounded under their own gravity.
Still, brightness and distance alone cannot establish its precise size. Further observations, particularly in infrared wavelengths, will help researchers determine its physical characteristics and whether it qualifies for the classification.
How the Vera C. Rubin Observatory detected the distant world
The discovery came from an analysis of observations collected by the Simonyi Survey Telescope at the Vera C. Rubin Observatory. On October 13, astrophysicist Matthew Holman identified the object while processing data with a computer program designed to track moving bodies.
The software compares billions of detections to identify observations that correspond to the same moving object. After noticing ED138’s unusual brightness and distance, Holman began checking the results to rule out possible errors.
Additional research uncovered more observations in Rubin’s own records, including images dating back to March 2026. Scientists also located the object in archival images from other surveys taken as early as 2016, allowing them to reconstruct more than a decade of its orbital path.
The object had remained difficult to identify because it appeared against a crowded region of the sky near the Milky Way’s plane, where millions of stars can obscure faint celestial bodies.
Why this discovery could change what scientists know about the solar system
The possible classification of ED138 is important beyond the number of dwarf planets in the solar system. Studying distant trans-Neptunian objects helps astronomers investigate how the solar system formed and how the giant planets influenced the movement of smaller bodies over billions of years.
ED138’s orbit is tilted by nearly 25 degrees relative to the plane of the solar system. Researchers classify it as a hot-classical trans-Neptunian object, a characteristic that suggests gravitational interactions with Neptune may have altered its original orbit.