The Vera Rubin Observatory, operating from Cerro Pachón in Chile, has identified a bright object far beyond Neptune that may belong to the dwarf‑planet class. Designated 2026 ED138, the body is estimated to measure between 600 and 1,500 kilometers (373–972 miles) in diameter, a size range that would allow its own gravity to pull it into a roughly spherical shape – the defining trait that separates dwarf planets from smaller asteroids.
Discovery and verification
Matthew Holman of the Center for Astrophysics | Harvard & Smithsonian discovered 2026 ED138 while processing archival Rubin data with a custom search algorithm he co‑developed with colleague Kevin Napier. The breakthrough occurred on 13 October, when the code flagged an unusually bright source beyond Neptune’s orbit. Holman described his initial reaction as “excited disbelief,” noting the rarity of such objects and immediately double‑checking the result for errors.
Further validation came from multiple observations. Holman and Rubin Solar System Lead Scientist Mario Jurić confirmed that the observatory captured the object on 30 separate occasions across 20 nights between 4 March and 11 July of this year. In addition, the Dark Energy Camera (DEC) on the Víctor M. Blanco 4‑meter Telescope at the Cerro Tololo Inter‑American Observatory recorded the object as far back as 2016, providing a longer observational baseline.
Orbital characteristics and context
Current calculations place 2026 ED138 at roughly 46 astronomical units (AU) from the Sun—well beyond Pluto’s average distance of about 40 AU. Its orbital plane is inclined about 25 degrees relative to the ecliptic, suggesting a past gravitational encounter with Neptune that may have tilted its trajectory.
The Vera Rubin Observatory began its ten‑year Legacy Survey of Space and Time (LSST) in June 2025, following first light in April 2025. Equipped with a 3.2‑gigapixel camera—the largest ever built for astronomy—the LSST repeatedly images the entire southern sky, creating a high‑resolution time‑lapse that aids studies of dark energy, dark matter, and solar‑system bodies. To date, Rubin has catalogued more than 11,000 new asteroids, and its systematic sky coverage is expected to uncover additional dwarf‑planet candidates like 2026 ED138.
Next steps and significance
Although the object’s brightness and distance suggest a substantial size, definitive classification as a dwarf planet hinges on precise measurements of its dimensions. Infrared observations, for which NASA’s James Webb Space Telescope is optimized, are required to refine size estimates and confirm whether the body meets the spherical‑shape criterion.
If confirmed, 2026 ED138 would join the five officially recognized dwarf planets—Pluto, Ceres, Eris, Haumea and Makemake—expanding a very exclusive group. Holman emphasized that Rubin’s decade‑long survey will repeatedly image the southern sky, increasing the likelihood of finding more hidden worlds in regions previously missed by older surveys.
The discovery underscores Rubin’s capability to detect faint, distant objects and highlights the growing inventory of the outer solar system. As additional data accumulate, astronomers anticipate further insights into the population, dynamics, and formation history of trans‑Neptunian bodies.
Norman Pearlstine is the Executive Editor and Co-Founder at News Raise. With over two decades of experience across financial journalism, corporate governance, and market analysis, Norman leads the editorial direction and ensures strict adherence to journalistic accuracy and ethics.
