NSF-DOE Rubin Observatory finds possible dwarf planet ED138

The National Science Foundation said NSF-DOE Vera C. Rubin Observatory had found a large object that scientists identified as a possible dwarf planet. A preliminary data analysis showed the object was orbiting in the outer reaches of the solar system beyond Pluto and may be one of the largest dwarf planet candidates ever found.

If confirmed, ED138 would join the five other known dwarf planets. They are Pluto, Ceres, Eris, Haumea and Makemake.

The announcement said Rubin Observatory is jointly funded by the U.S. National Science Foundation and the U.S. Department of Energy's Office of Science. The International Astronomical Union Minor Planet Center gave the newly discovered object the provisional designation ED138.

According to the announcement, the discovery was enabled by Rubin's speed and its enormous camera, the largest ever created. The camera can capture every visible change in the southern hemisphere sky and precisely record movement among objects and phenomena.

ED138 was found in a region of sky close to the plane of the Milky Way. The region is visually filled with millions of stars and was likely why the object was not discovered until now. Rubin's regular monitoring and data algorithms allowed scientists to spot ED138 moving within the crowded field.

Edward Ajhar, NSF Program Director for Rubin Observatory, said the observatory's ability to capture movement and change among a vast number of objects extends scientists' ability to reveal and understand new things about the solar system, the Milky Way and other galaxies across the universe.

Scientists using other observatories can now make follow-up observations of ED138 to learn more about its nature. ED138 is one of many solar system objects discovered by Rubin this year. In April, Rubin submitted observations of over 11,000 new asteroids. The National Science Foundation published the announcement Tuesday 27 October 2026.