Possible dwarf planet discovered beyond Pluto
Astronomers have discovered a large icy object beyond Pluto that could qualify as a dwarf planet, potentially adding a new member to the solar system's officially recognized group.
The discovery was announced on Thursday by the US-funded Vera C. Rubin Observatory in Chile, which houses the world's largest 3.2-gigapixel digital camera, built specifically for astronomy. Researchers estimate that the object, provisionally named 2026 ED138, is between 600 and 1,500 km in diameter and may be one of the largest dwarf planet candidates ever found.
The object currently sits roughly 46 times farther from the Sun than Earth. Pluto's average distance, for comparison, is about 40 times Earth's. The object likely escaped detection until now because it appeared against a crowded backdrop of millions of stars near the plane of the Milky Way.
Discovery Challenges
Rubin's repeated images and tracking software has now allowed scientists to pick out the object's movement. If confirmed, ED138 would join five dwarf planets recognized by the International Astronomical Union, which include Eris, Haumea, Makemake, Ceres, and Pluto, which was considered the solar system's ninth planet until it was reclassified in 2006.
Next Steps
To narrow down the true size of the object, researchers could use Chile's ALMA telescope which can detect radiation emitted by ED138 itself, helping get a more accurate measurement. The last dwarf planet officially recognized by the International Astronomical Union was Haumea in 2008.
Other candidates have since emerged, including 2017 OF201, whose discovery was announced in May 2025, but none have yet been formally added to the list. Astronomers still need more research and better measurements before determining ED138's status.
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