Astronomers have announced the discovery of a massive new dwarf planet candidate lurking in the frigid depths of our solar system far beyond Neptune. Identified by its provisional designation 2026 ED138, the mysterious icy object was found using powerful instruments at the newly operational NSF-DOE Vera C. Rubin Observatory.
The discovery was formally revealed during a meeting of the American Astronomical Society’s division for planetary sciences in Spokane, Washington. If upcoming observations verify its size and rounded shape, 2026 ED138 could join an exclusive group of just five other officially recognized dwarf planets in our solar system: Pluto, Ceres, Eris, Haumea, and Makemake.
How the New Object Was Found
The cosmic object was detected by running billions of data points collected by the Rubin Observatory through an advanced search code. The algorithm was developed by Center for Astrophysics | Harvard & Smithsonian astronomers Matthew Holman and Kevin Napier. Holman initially experienced “excited disbelief” upon spotting the signal, prompting him to run thorough checks to ensure the data was accurate.
The candidate object is estimated to measure between 600 and 1,500 kilometers (approximately 373 to 932 miles) across. Scientists note that this size is likely large enough for gravity to have sculpted the body into a sphere, fulfilling a key physical requirement that distinguishes dwarf planets from smaller space rocks and asteroids.
Despite its considerable size, 2026 ED138 managed to evade detection for decades. It remained hidden because its orbital path is located in a crowded region of the night sky where dense background starlight completely drowned out its faint reflection.
Significance and Future Observations
The discovery was made during preparations for the Rubin Observatory’s Legacy Survey of Space and Time, a comprehensive 10-year survey mapping the southern sky. The object’s tilted orbit indicates that it was likely displaced from its original path long ago through gravitational interactions with Neptune.
Astronomers will now conduct follow-up observations using other telescopes to confirm the exact dimensions, mass, and round morphology of 2026 ED138. Researchers believe that as the Vera C. Rubin Observatory continues its sky survey, it may uncover many more hidden worlds waiting in the distant reaches of the outer solar system.
