Astronomers have reported the possible identification of a new dwarf planet, designated 2026 ED138, located in the far reaches of our Solar System, beyond Pluto’s orbit. If confirmed, this celestial body could be one of the largest dwarf planets detected in this segment of space.

Discovery by the Vera C. Rubin Observatory

The Vera C. Rubin Observatory, equipped with the world’s largest digital camera, is at the forefront of this discovery. Recently, it commenced a significant survey of the southern sky, aimed at unveiling new astronomical phenomena.

Unveiling 2026 ED138

As a trans-Neptunian object, 2026 ED138 orbits the Sun well past Neptune, the Solar System’s outermost planet. This discovery was made during preparations for the observatory’s Legacy Survey of Space and Time—a decade-long initiative to meticulously map the southern hemisphere sky.

Matthew Holman from the Center for Astrophysics | Harvard & Smithsonian observed the celestial body during data analysis on October 13, 2026. Employing a specialized code, he compared billions of space detections to identify the consistent positional signatures of ED138, noting its significant brightness and size.

“Rubin Observatory’s super power is the ability to clearly capture movement and change among a vast number of objects and phenomena that humans have never seen before,” commented Edward Ajhar, NSF Program Director for the Rubin Observatory.

Characteristics of 2026 ED138

Current calculations suggest that 2026 ED138 is approximately 600 to 1,500 kilometers (370 to 930 miles) in diameter. Its current position is around 46 astronomical units (AU) from the Sun—where 1 AU is the average distance from Earth to the Sun, significantly farther than Pluto’s 40 AU orbit.

Additionally, the object’s orbit is tilted by nearly 25 degrees relative to the plane of the Solar System, categorizing it as a ‘hot-classical trans-Neptunian object.’ This inclination hints at a history of gravitational disturbances from nearby Neptune that may have altered its original trajectory.

The Search for New Celestial Bodies

The discovery of 2026 ED138 exemplifies the effectiveness of the Rubin Observatory’s ongoing surveys. This facility continuously monitors the entire southern sky, utilizing advanced algorithms to sift through data from millions of stars and potential celestial bodies.

Preliminary findings indicate that ED138 may be one of the largest dwarf planets found in the outer Solar System, pending further infrared observations to validate its size and classification.

Potential Confirmation as a Dwarf Planet

For a celestial body to be classified as a dwarf planet, it must possess sufficient mass to maintain a rounded shape due to its own gravity. If ED138 meets these criteria upon further investigation, it will join a select group of known dwarf planets, including Pluto, Haumea, Makemake, Eris, Ceres, and Vesta.

Holman elaborated on the significance of this discovery: “If confirmed as a dwarf planet, ED138 would join a very small family of worlds.” As the Rubin Observatory continues its expansive sky surveys, there may be additional undiscovered objects awaiting detection.