Potential New Dwarf Planet Identified in Rubin Observatory Data
Amateur astronomers tracking the outer edges of the solar system are preparing to observe a potential new dwarf planet pass in front of a distant star on Halloween, following its recent identification in data from the Vera C. Rubin Observatory, sciencenews.org reported.
- The Vera C. Rubin Observatory detected an object, designated 2026 ED138, orbiting billions of kilometers beyond Pluto.
- Archival images from 1954 and 2016 allowed researchers and amateur astronomers to reconstruct its 280-year orbit.
- An occultation on Halloween will provide critical data regarding the size, shape, and potential presence of moons around the object.
Mapping the Outer Fringes of the Solar System
Perched on a mountaintop in Chile, the Vera C. Rubin Observatory began its planned ten-year survey in June 2026 after capturing initial test images in June 2025. Between March 4 and July 11, the facility’s telescope recorded the motion of an unrecognized object 30 times across 20 nights. Smithsonian Astronomical Observatory astrophysicist Matt Holman identified the moving dot of light on October 13 while searching through the observatory data.
The object, cataloged as 2026 ED138, sits approximately 47 times farther from Earth than Earth is from the sun. Based on its brightness, astronomers estimate its width spans between 600 and 1,500 kilometers. That scale places it in a size tier comparable to acknowledged dwarf planets such as Ceres and Makemake, rendering it large enough for its own gravity to pull it into a spherical shape. “It’s really big. It’s damn huge,” said amateur astronomer Sam Deen. “No matter what you call it, it’s still the biggest thing we’ve found in the entire solar system in 19 years.”
Recovering Decades of Hidden Astronomical Data
Verifying the physical reality of 2026 ED138 required pulling historical observations from astronomical archives. Holman and his colleagues located the object in archived data gathered in 2016 by the Dark Energy Camera situated on a neighboring mountain peak in Chile. Deen subsequently tracked the body back further, identifying it on photographic plates exposed in 1954 during a sky survey at the Palomar Observatory in California. Independent checks by other amateur astronomers confirmed the 1954 and 2016 sightings.
The object went unnoticed for decades because it travels slowly across the night sky, taking 280 years to complete a single orbit around the sun. Its imperceptible shift from night to night coincided with a dense background of Milky Way stars, masking its position. Combining observations spanning more than 70 years allowed researchers to calculate its trajectory with high precision.
Detecting Neptune Trojans Amid the Milky Way
Alongside the dwarf planet candidate, researchers at the American Astronomical Society’s Division of Planetary Sciences meeting in Spokane, Washington, detailed the discovery of new Neptune Trojans. These icy objects share Neptune’s orbital path. Planetary scientist Meg Schwamb explained that trailing cloud formations had drifted in front of the Milky Way from Earth’s viewpoint over the past 15 years.
Analyzing early commissioning data from the Vera C. Rubin Observatory, Schwamb’s team found new trailing Trojans. These objects are thought to preserve an ancient record of planetary formation.
Satellite Interference Threatens Future Deep-Sky Surveys
As the Vera C. Rubin Observatory continues its decade-long survey, astronomers face growing operational hurdles. Deen plans to observe 2026 ED138 pass directly in front of a distant star on Halloween. Such occultations allow scientists to measure the physical dimensions, surface boundaries, and potential moon systems of distant planetary bodies with exceptional accuracy.