4 Nov 2026

The candidate orbits our Sun beyond Pluto, and may be among the largest and brightest objects discovered in this region of the solar system

Scientists at the Center for Astrophysics | Harvard & Smithsonian have discovered 2026 ED138, a large, bright trans-Neptunian object they've identified as a dwarf planet candidate.

The observations were announced Oct. 27 by the International Astronomical Union's Minor Planet Center. If confirmed, ED138 would be among the largest dwarf planets ever discovered in this region of the solar system.

The candidate was found by CfA astronomer Matthew Holman using the Legacy Survey of Space and Time (LSST) at the NSF–DOE Vera C. Rubin Observatory. The candidate’s distance from the Sun places it beyond the orbit of dwarf planet Pluto. Initial analysis indicates that it may be among the largest and brightest bodies scientists have discovered in this region of the solar system.

On the evening of 13 October, Holman was running data collected by Rubin earlier in 2026 through a search code he developed with CfA colleague Kevin Napier. The code is built to look at billions of detections of moving objects, compare them, and find the detections that correspond to the same object. Using this method, Holman uncovered ED138, and he immediately noticed that its brightness and distance indicated that it is unusually large.

“My first reaction was one of excited disbelief,” says Holman. “Objects like this are very rare, so I immediately started checking whether I or the code had done something wrong. If confirmed as a dwarf planet, ED138 would join a very small family of worlds. Rubin will image the whole southern sky again and again for ten years, so any others hiding in the places earlier surveys skipped are now within reach.”

[Image]

A student at JD Price Elementary School looks through the STARS telescope, as STARS team member Jason Gurtman looks on.