Astronomers using a cutting-edge survey telescope in Chile have detected a massive candidate dwarf planet lurking in the frozen fringes of the solar system beyond Pluto, researchers announced this month.
The newfound object, provisionally cataloged as 2026 ED138, circles the sun at an average distance of approximately 46 astronomical units, or 46 times the distance separating Earth from the sun. If subsequent checks verify its round shape and dimensions, the world would expand the roster of officially recognized dwarf planets in the solar system to six, according to reports by CNN and Live Science.
A world hidden in plain sight
Scientists estimate the newly spotted body measures between 370 and 930 miles across, based on its distance, surface brightness and estimated reflectivity. That scale places the object well above the size of Ceres, the smallest recognized dwarf planet at roughly 595 miles in diameter, and potentially more than half the width of Pluto, which spans 1,477 miles.
Matthew Holman, a senior astrophysicist at the Center for Astrophysics | Harvard & Smithsonian, spotted the anomaly on Oct. 13 while using search software to scan through billions of observations gathered by the Vera C. Rubin Observatory. The facility, perched on an 8,800-foot mountain in Chile, houses the largest digital camera ever constructed and began scanning the southern sky earlier this year.
“My first reaction was one of excited disbelief,” Holman said in a statement reported by Live Science and BBC Sky at Night Magazine. “Objects like this are very rare, so I immediately started checking whether I or the code had done something wrong.”
Collaborating with Mario Jurić, the solar system lead scientist for the Rubin Observatory, Holman retrieved 20 additional sightings dating to March. The team later traced the object’s path back 10 years by combing through archival exposures collected by the Victor M. Blanco 4-meter Telescope’s Dark Energy Camera, also situated in Chile.
Camouflaged by the Milky Way
Despite being bright enough for skilled amateur observers with telescopes to view, the icy world escaped detection for decades because of its unusual trajectory. Its orbit is inclined roughly 25 degrees relative to the main solar system plane, causing it to cross the dense star fields of the inner Milky Way from Earth’s viewpoint.
“For the last 20 years, the object has kind of been looping its way across the Milky Way, from our point of view,” Holman told CNN, noting that search programs rarely target that crowded band because millions of stars make identifying moving bodies exceptionally difficult. Most major sky surveys have also historically operated in the Northern Hemisphere.
The candidate belongs to the Kuiper Belt, a vast ring of icy debris, methane and rock situated beyond Neptune. The International Astronomical Union currently recognizes five official dwarf planets: Pluto, Eris, Haumea, Makemake and Ceres. Under rules established in 2006, a dwarf planet must orbit the sun and possess enough gravitational mass to pull itself into a spherical shape, but unlike full planets, it does not clear its orbital neighborhood.
Next steps for confirmation
Researchers caution that confirmation will take time. Astronomers must gather precise infrared measurements over the coming months to accurately establish the object’s diameter, density and physical structure, CNN reported.
Rubin’s 10-year Legacy Survey of Space and Time is expected to uncover tens of thousands of distant icy bodies, including several additional dwarf planet candidates. If the discovery is formally ratified by the International Astronomical Union, the organization will issue a permanent catalog number before opening the naming process.
