Dwarf planet candidate discovered beyond Pluto's orbit

According to preliminary estimates, the object's diameter ranges from 600 to 1,500 km. It is about 46 times farther from the Sun than Earth is, whereas for Pluto this figure averages around 40. The body's orbit is inclined by about 25 degrees. Researchers suggest that such an inclination may be linked to the gravitational influence of Neptune.

The object was identified by astrophysicist Matthew Holman from the Harvard-Smithsonian Center for Astrophysics. He processed data from the observatory on Cerro Pachón using a search algorithm that he developed together with Kevin Napier. A re-examination revealed another 30 images of the body taken by the Rubin Observatory between March and July 2026. Observations dating back to 2016 were also found in the archives of other instruments. The object had not been noticed before because it is located in a densely star-filled region of the sky.

2026 ED138 has not yet been recognized as a dwarf planet. Scientists must confirm that its mass is sufficient for its own gravity to pull it into a nearly spherical shape. Its size has so far been calculated based on its brightness, distance, and assumed surface reflectivity. Infrared observations are needed to refine these figures, and radio observations using the ALMA array in Chile are also being considered.

The International Astronomical Union currently officially recognizes five dwarf planets: Pluto, Eris, Haumea, Makemake, and Ceres. "If ED138's status as a dwarf planet is confirmed, it will join a very small family of celestial bodies," Holman said.