World’s largest digital camera spots dwarf planet candidate beyond Pluto
ED138 is currently about 46 times farther from the sun than Earth. Scientists say it is among the largest objects discovered beyond Neptune.
Astronomers discovered a dwarf planet candidate, called ED138, beyond the orbit of Pluto with the new Vera C. Rubin Observatory. It is estimated to be over 4.2 billion miles away from the sun.
A distant world hiding among millions of background stars could become the solar system’s newest recognized dwarf planet, following its discovery in images from the Vera C. Rubin Observatory.
The object, provisionally named 2026 ED138, is currently about 46 times farther from the sun than Earth. Scientists estimate it measures roughly 370 to 930 miles across, potentially placing it among the largest objects discovered beyond Neptune.
Our solar system's most famous dwarf planet, Pluto, is about 751 miles in diameter and 39 times farther from the sun than the Earth, according to NASA.
A model of the solar system showing the orbital pathway of newly discovered dwarf planet candidate ED138. ED138 was discovered in observational data from NSF–DOE Vera C. Rubin Observatory spanning 4 March–11 July 2026. The time then elapses at a rate of one Earth-year per 30 seconds. (NSF–DOE Vera C. Rubin Observatory/NOIRLab/SLAC/AURA/R. Proctor. Orbit data provided by the IAU Minor Planet Center (MPCorb catalog), funded by NASA PDCO and the Tamkin Foundation. Star map: NASA/Goddard Space Flight Center Scientific Visualization Studio. Gaia DR2: ESA/Gaia/DPAC.)
Its size remains uncertain because researchers do not yet know how reflective its surface is. Infrared observations are needed to refine that estimate and confirm its nature. A key requirement for dwarf planets is enough mass for gravity to pull them into a rounded shape.
Matthew Holman of the Center for Astrophysics at Harvard & Smithsonian identified the object on Oct. 13 while analyzing earlier Rubin observations.
“My first reaction was one of excited disbelief,” Holman said.
A model of the Solar System showing the orbital pathway of newly discovered dwarf planet candidate 2026 ED138. The model also shows the orbits of the five dwarf planets recognized by the International Astronomical Union (IAU): Pluto, Ceres, Eris, Haumea, and Makemake. (Image credit: NSF–DOE Vera C. Rubin Observatory/NOIRLab/SLAC/AURA/R.)
There are currently five dwarf planets recognized by the International Astronomical Union: Pluto, Ceres, Eris, Haumea and Makemake. This new planet would mark the sixth and potentially the largest.
How astronomers tracked down new dwarf planet
NSF–DOE Vera C. Rubin Observatory is seen with its dome open during First Look observation activities in April 2025. Messier 41, the Little Beehive Cluster, can be seen over the telescope in this telelens photo. (Image credit: RubinObs/NOIRLab/SLAC/NSF/DOE/AURA/P. Horálek (Institute of Physics in Opava)
Researchers found 30 Rubin observations spanning March through July. Archival images dating to 2016 helped trace its orbit. The object likely escaped earlier detection because it appeared against a crowded stretch of the Milky Way.
Perched on a mountaintop in Chile, Rubin uses the world’s largest digital camera, a 3,200-megapixel instrument that captures a detailed image approximately every 40 seconds.
Rubin began its 10-year Legacy Survey of Space and Time in June, launching a mission to create the most detailed time-lapse record of the cosmos ever made. During about six weeks of early testing, the observatory discovered more than 11,000 previously unknown asteroids, including 33 near-Earth objects and 380 trans-Neptunian objects, according to the SLAC National Accelerator Laboratory.
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