First dwarf planet candidate discovered by Rubin
Published 27 October 2026
Rubin Observatory has found 2026 ED138 – a large, bright trans-Neptunian object that scientists have identified as a dwarf planet candidate.
Rubin Observatory has found 2026 ED138 – a large, bright trans-Neptunian object that scientists have identified as a dwarf planet candidate.
The observations were announced by the International Astronomical Union Minor Planet Center (MPC). If confirmed, ED138 would be among the largest dwarf planets ever discovered in this region of the Solar System.
The candidate was found during observations taken during the run up to the Legacy Survey of Space and Time (LSST) by Rubin Operations team member and in-Kind contributor Matthew Holman (Center for Astrophysics | Harvard & Smithsonian [CfA]). It has been given the provisional designation 2026 ED138 (ED138). 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.
Jamie Robinson, a Postdoctoral Research Associate at the Royal Observatory Edinburgh, is the LSST:UK Community Scientist and has an interest in small solar objects. He said: Rubin is bringing us closer to completing the inventory of these large trans-Neptunian objects (TNO). The physical properties of these large objects and the orbits on which they are found are excellent constraints for how they formed and grew in the dusty and gassy early Solar System disk, and how they have evolved dynamically under the gravitational influence of the planets.”
Planetary scientist Megan Schwamb is based at the Astrophysics Research Centre (ARC) at Queen’s University Belfast. She said “It's not so surprising that Rubin Observatory found a bright large TNO. Analysis of past wide-field surveys that were much shallower than Rubin, predicted that the inventory of these large bright objects was mostly complete with one or two left to be found in the less well searched Galactic plane and parts of the Southern night sky. Rubin Observatory is just doing its job really well inventorying the Solar System to new depths. But I was surprised that it found such an object so early in the commissioning observations. This was not on my bingo card for this year!”
Read the full story at the Rubin Observatory website