Possible New Dwarf Planet ED 183 Found in Southern Sky Using Vera C. Rubin Telescope

Somewhere in the data from a telescope on a Chilean mountaintop, a moving dot turned up that astronomers had not seen before. The object is provisionally named 2026 ED 183, and it may turn out to be one of the largest dwarf planets ever found in the solar system. For now, it is only a candidate.

The find came from the Vera C. Rubin telescope, which sits atop an 8,800-foot mountain in Chile. Astrophysicist Matthew Holman, a lecturer at Harvard University, ran a computer program through everything the telescope collected in 2026. The software sifted through billions of moving objects. Then ED 183 surfaced. Holman has described his first reaction as excited disbelief, and he immediately checked whether something had gone wrong.

Nothing had. Working with scientist Mario Jurić, Holman traced 20 additional sightings of the object, reaching back to March 2026.

The size estimate is wide: between 370 and 930 miles across. At the upper end, the object would be wider than the length of the UK. That range is why it could land among the biggest dwarf planets known. If it is confirmed, it would join Ceres, Pluto, Haumea, Makemake and Eris.

Two things kept it hidden. It travels through the Milky Way, where the density of stars makes moving objects very hard to pick out. As Holman put it, people don't typically search there for exactly that reason. It also lies in the southern sky, and most telescopes survey the northern one.

It cannot be seen with the naked eye. Holman says it is bright enough that really capable amateurs could spot it if they know where to look.

Holman is careful about the status. In his words, it is still a candidate, and astronomers need to know how physically big it is. He expects that to take a few months, probably. Only if it is granted official dwarf planet status would it receive a new name, likely a Greek one. Who would choose that name is still unclear. Holman says people have already emailed him suggestions, and some are names already used by other objects. He would like to propose something, he says, but isn't holding his breath, given the scale of the project.

Michele Bannister, an associate professor who was not involved in the discovery, called it a really cool world. She imagined that a spacecraft might one day find a nitrogen glacier there, as on Pluto. But she was plain about the limits of current knowledge: all that is known is that it is big, and anything beyond that is speculation about its physical characteristics for now.

The next step is measurement. Over the coming months, astronomers will work to pin down the object's actual size, which will decide whether 2026 ED 183 earns the title and a name.