Rubin Observatory Finds Possible Dwarf Planet Beyond Pluto
publishers 34articles 36first reported 27 Oct, 19:19 UTCdeveloping since 28 Oct · 5 editions
Scientists using the Vera C. Rubin Observatory in Chile have identified an icy object beyond Pluto that could qualify as a dwarf planet, researchers announced Wednesday.
The candidate, designated 2026 ED138, is estimated to be about 600 to 1,500 kilometers (370 to 930 miles) wide and orbits at roughly 46 times Earth’s distance from the sun. Pluto, by comparison, averages about 40 times Earth’s distance from the sun.
Astrophysicist Matt Holman of the Center for Astrophysics | Harvard & Smithsonian first spotted the object in observations from Rubin, a joint initiative of the U.S. National Science Foundation and Department of Energy. The discovery was announced at a scientific meeting in Spokane, Washington.
Further observations are needed to determine the object’s physical size and confirm whether its gravity has pulled it into the rounded shape required for dwarf-planet classification. Its brightness alone cannot settle its size because a smaller, highly reflective body can appear as bright as a larger, darker one. Holman said observations at longer wavelengths, including with Chile’s ALMA telescope, could help provide a more precise measurement.
If confirmed, 2026 ED138 would join the five dwarf planets recognized by the International Astronomical Union: Pluto, Eris, Haumea, Makemake and Ceres. Current estimates would place the newly discovered object among the largest members of that group.
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