Rubin Observatory finds possible new dwarf planet beyond Neptune

Astronomers using data from the Vera C. Rubin Observatory in Chile have discovered an icy world that could become the solar system's sixth confirmed dwarf planet. The object, known as 2026 ED138, orbits far beyond Neptune and Pluto.

Matthew Holman of the Harvard & Smithsonian Center for Astrophysics found the object on October 13 while running previously collected Rubin data through a search code he developed with colleague Kevin Napier. The discovery was announced on October 27.

The object currently sits about 46 astronomical units from the sun, well beyond Pluto's current distance of roughly 40 AU. Scientists estimate its diameter at between 600 and 1,500 kilometers, or 373 to 972 miles.

At that size, the object likely has enough gravity to pull itself into a round shape, a key physical criterion for dwarf planet status. Astronomers believe it formed closer to the sun billions of years ago before Neptune's gravity flung it into a wider orbit.

Only five dwarf planets have been confirmed to date: Pluto, Ceres, Eris, Haumea, and Makemake. If confirmed, 2026 ED138 would join that small group.

Rubin Observatory scientist Mario Jurić said the facility's speed, depth, and precision give astronomers an unprecedented ability to explore the sky. He added that once an object is identified, researchers can search back through old images to find it where nobody previously looked.