Rubin Observatory Data Reveals 2026 ED138, a Possible Sixth Dwarf Planet
A search of Vera C. Rubin Observatory data has turned up 2026 ED138, an object about 46 times farther from the Sun than Earth and up to 1,500 kilometers wide, that may qualify as the solar system's sixth recognized dwarf planet.
The object lies roughly 46 times farther from the Sun than Earth, putting it beyond Pluto, which orbits at about 40 times Earth's distance. Initial measurements put its diameter between 600 and 1,500 kilometers, or 373 to 932 miles. It escaped detection for years because it sits against a particularly crowded field of Milky Way stars whose light drowned it out.
The find came from running billions of pieces of Rubin Observatory data through a search code written by Matthew Holman and Kevin Napier, astronomers at the Center for Astrophysics | Harvard & Smithsonian. "My first reaction was one of excited disbelief," Holman said in a statement. "Objects like this are very rare, so I immediately started checking whether I or the code had done something wrong."
When Holman and Mario Juric of the University of Washington went back to double-check, they found 30 additional Rubin observations of the object dating to between March and July 2026. Turning to other observation tools, the pair found further sightings going back to 2016. Together the data let the astronomers begin mapping 2026 ED138's orbit.
The object's path is tilted about 25 degrees off the plane of the solar system, an arrangement that could be tied to disruptions caused by Neptune's gravitational pull. Its size places it among the largest dwarf planet candidates detected so far.
Size alone does not settle the question. Further observations are needed to establish whether 2026 ED138 has enough mass to be pulled into a round shape, a key requirement for dwarf planet status.