Astronomers using Chile’s Vera C. Rubin Observatory have detected 2026 ED138, a candidate dwarf planet located 4.3 billion miles from the Sun that, if verified as spherical, would be the first addition to the solar system’s dwarf planet family since 2006.
LA SERENA, Chile — Deep in the freezing, dark frontiers beyond Pluto, astronomers have detected a previously unknown celestial body that may soon join the solar system’s recognized family of dwarf planets.
The Vera C. Rubin Observatory announced Tuesday that researchers have uncovered compelling evidence of an undiscovered world situated approximately 4.3 billion miles from the Sun—roughly 46 times the distance between Earth and its star.
Provisionally designated 2026 ED138, the body represents the first candidate dwarf planet identified since the International Astronomical Union (IAU) formally established the classification in 2006.
“My first reaction was one of excited disbelief,” said Matthew Holman, an astrophysicist at the Center for Astrophysics | Harvard & Smithsonian in Cambridge, Massachusetts. “Objects like this are very rare, so I immediately started checking whether I or the code had done something wrong.”
A Tilted Path in the Deep Solar System
Preliminary telemetry indicates that 2026 ED138 spans a diameter between 370 and 930 miles, placing it as a mid-sized member among known trans-Neptunian bodies. By comparison, the two largest recognized dwarf planets, Pluto and Eris, each measure over 1,400 miles across.
Astronomers caution that additional observations are required to confirm its planetary status. Under IAU guidelines, researchers must verify that the object possesses sufficient mass and self-gravity to achieve hydrostatic equilibrium—pulling itself into a nearly spherical shape to distinguish it from irregular asteroids.
The candidate world also follows an unusual trajectory: its orbital plane is tilted 25 degrees relative to the primary ecliptic disk of the solar system, meaning it traces a steep diagonal circuit around the Sun compared to the major planets.
A Needle Found in a Digital Haystack
The breakthrough marks an early milestone for the Vera C. Rubin Observatory, perched atop Cerro Pachón in the Chilean Andes. The facility conducts automated, continuous surveys of the Southern Hemisphere sky using the largest digital camera ever constructed—a 3.2-gigapixel optical powerhouse.
While 2026 ED138 reflects sufficient sunlight to be seen by standard telescopes, spotting it amid millions of distant background stars proved virtually impossible until Rubin’s high-throughput imaging pipeline detected its motion. Sophisticated orbital tracking software flagged the shifting point of light across successive frames. Once identified, researchers cross-referenced archival exposures from other observatories to map its trajectory and estimate its dimensions.
The Hunt for Further Worlds
Astronomers note that the identification of 2026 ED138 neither confirms nor refutes the existence of “Planet Nine”—a hypothetical, Neptune-sized world theorized to orbit in the far reaches of the Kuiper Belt. However, researchers view the detection as a proof of concept for surveying the outer solar system.
“It is evidence that we have the capacity to find things and that there are amazing things left to be found,” Holman said. “There could easily be a Mars-sized object out there that just hasn’t been found yet, or bigger.”
