A potential new dwarf planet, provisionally called ED138, has been spotted by astronomers using the Vera C. Rubin Observatory. This massive object orbits far beyond Pluto and was identified during a large-scale data analysis conducted in early 2026.
A 600-kilometer giant hiding in the Milky Way
ED138 is a massive candidate object that could fundamentally change our understanding of the outer solar system.. Measuring between 600 and 1,500 kilometers in diameter, the object is significantly larger than the dwarf planet Ceres. According to the report, the object's location in the southern hemisphere and its position along the plane of the Milky Way made it nearly impossible for previous telescopes to spot it among the dense star fields.
Matthew Holman, a senior astrophysicist at the Smithsonian and Harvard lecturer, discovered the object while analyzing massive datasets. He used a custom-coded computer program to sift through billions of detections to find this specific moving object. Because the object has been looping across the Milky Way for the last 20 years, the sheer number of stars in its path previously obscured its presence from researchers.
The Vera C. Rubin Observatory's three-day sky scan
The Vera C. rubin Observatory in Chile is revolutionizing how we map the heavens through high-speed imaging. By utilizing the world's largest digital camera, the facility can image the entire sky every three days. This rapid cadence allows for the detection of objects like ED138 that might otherwise remain hidden in the vastness of space.
Megan Schwamb of Queen's University Belfast noted that the observatory is performing its inventory of the solar system with unexpected efficiency. As the report states, the discovery was a surprise even to the Rubin Solar System Operations team during their early commissioning phase. The facility, which began operating in 2025, is expected to transform our view of the solar system over the coming decade.
Joining the ranks of Ceres, Pluto, and Eris
If confirmed, ED138 will become the sixth recognized dwarf planet in our solar system. To meet the International Astronomical Union (IAU) criteria, an object must orbit the sun, be nearly round, and not have cleared its orbital path of debris. This definition was famously used in 2006 to demote Pluto, shifting the solar system from nine planets to eight.
The International Astronomical Union (IAU) currently recognizes five such bodies: Ceres, Pluto, Haumea, Makemake, and Eris. ED138, which orbits at approximately 46 astronomical units, sits well beyond Pluto in the trans-Neptunian region. Michele Bannister of the University of Canterbury noted that the object's size puts it right in the range where scientists can begin to consider it a true world.
The uncertainty of ED138's exact diameter and name
Researchers still face several hurdles before ED138 can be officially classified as a dwarf planet. While Mario Jurić of the University of Washington helped confirm 20 additional observations dating back to March 2026, scientists still need to determine the object's exact physical dimensions. as reported by the source, obtaining these measurements could take several months of additional study.
The naming process for ED138 remains a significant unknown for the scientific community. while Holman mentioned that suggestions are already being submitted, the specific protocols for how the International Astronomical Union will assign a permanent name and number are not yet clear. For now, the object remains a high-interest candidate that other telescopes are prepared to investigate.
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