Astronomers examining early survey data from the Vera C. Rubin Observatory in Chile have detected a massive icy body beyond Pluto that could soon rank as the newest dwarf planet in the solar system, scientists announced this week.
The candidate world, provisionally cataloged as 2026 ED138, travels through the Kuiper Belt, a vast ring of frigid debris encircling the outer solar system. If confirmed by the International Astronomical Union, it would become only the sixth officially recognized dwarf planet, joining Ceres, Pluto, Eris, Haumea and Makemake.
A rare find in the dark
Researchers estimate the object measures between 370 and 930 miles in diameter, or roughly 600 to 1,500 kilometers, Phys.org reported. At that scale, internal gravity would be strong enough to pull the icy body into a spherical shape, fulfilling a central requirement for dwarf planet classification.
Mario Jurić, an astronomy professor at the University of Washington and lead of Rubin’s solar system team, called the object the largest trans-Neptunian body discovered in roughly two decades. “Finding an object this big, roughly 1,000 kilometers [621 miles] across, is something that happens maybe once in a generation,” Jurić said in a statement reported by Gizmodo.
Matthew Holman, a senior astrophysicist at the Harvard & Smithsonian Center for Astrophysics, first spotted the distant object on Oct. 13 while testing search algorithms he developed alongside colleague Kevin Napier. The software scans Rubin data to track moving points of light across billions of detections.
“My first reaction was one of excited disbelief,” Holman said in a statement quoted by Phys.org. “Objects like this are very rare, so I immediately started checking whether I or the code had done something wrong.”
Hiding in plain sight
The distant body is currently around 46 astronomical units from the sun, with one astronomical unit equal to the average distance between Earth and the sun, according to Phys.org. Pluto orbits at an average distance of 40 astronomical units.
Data logged by the Minor Planet Center shows that 2026 ED138 takes approximately 281 years to complete a single trip around the sun, the New York Post reported. Its orbit is elliptical and strongly tilted, swinging between 36.86 astronomical units at perihelion and 49.04 astronomical units at aphelion.
The path is also inclined roughly 24.5 degrees relative to the ecliptic plane where most major planets travel. Traditional sky surveys tend to concentrate their lenses along that flat plane, allowing tilted objects to spend decades outside routine observation fields. The object was also obscured by the crowded star fields of the Milky Way, where its faint glow blended into the starry backdrop.
Following the initial detection, Jurić reviewed archive files and identified 20 additional sightings in Rubin observations taken between March and July, Gizmodo reported. Researchers then located the object in older sky surveys, including images captured by the Dark Energy Camera as far back as 2016. Those earlier records provided a decade-long baseline that allowed researchers to calculate its trajectory with high precision.
The frontier of the solar system
The Vera C. Rubin Observatory, located on Cerro Pachón in Chile, features the largest digital camera ever constructed for astronomy. The facility began its 10-year Legacy Survey of Space and Time in late June, repeatedly imaging the southern sky every few days.
Trans-Neptunian objects are considered pristine leftovers from the dawn of the solar system, providing clues to planetary migration and orbital dynamics billions of years ago. Further measurements are needed to narrow the exact dimensions of 2026 ED138 before astronomers can formally confirm its status as a dwarf planet.
