Sixth possible dwarf planet found: Here's everything to know

Astronomers may have found a new member of our solar system’s dwarf planet family. 

The distant, icy object, provisionally designated 2026 ED138, was discovered in data from the Vera C. Rubin Observatory in Chile, and if confirmed, it would join Pluto, Ceres, Eris, Haumea, and Makemake as the sixth recognized dwarf planet.

The object is thought to be anywhere between 600 and 1,500 kilometers (370 and 930 miles) in size and may turn out to be one of the biggest TNOs discovered in the last two decades and probably bigger than the smallest known dwarf planet called Ceres. 

The TNO orbits the Sun at around 46 AU, which is further away from the Sun than Pluto's average of 40 AU.

The senior astrophysicist at the Harvard & Smithsonian Center for Astrophysics, Matthew Holman, detected the object while going through the Rubin survey data with the help of his code. 

"My first reaction was one of excited disbelief," said Matthew. Matthew's colleague at the University of Washington, Mario Jurić, located 20 more observations made since March 2026, and the archived data helped to map the orbit of the object for more than ten years.

This TNO remained undetected because it is located in the southern hemisphere, which was not well covered in previous surveys, and the location of the TNO is close to the galactic plane where millions of stars obscure moving objects.

Confirmation is not yet assured. To qualify as a dwarf planet, an object must be massive enough for gravity to pull it into a round shape.