Researchers Identify Potential Sixth Dwarf Planet Candidate ED138
New data analysis reveals a massive trans-Neptunian object hiding in plain sight.
1Discovery of Candidate ED138
Researchers at the Vera C. Rubin Observatory identified a potential sixth dwarf planet, designated ED138. Team member Matthew Holman discovered the object while utilizing a custom program designed to scan for moving celestial bodies. This candidate represents a significant find, as only five dwarf planets are currently recognized within our solar system.
2Verification Through Historical Data
Following the initial detection, Holman cross-referenced archived data to confirm the object's existence. He successfully located ED138 in observations dating back to 2016 using the Dark Energy Camera and the Asteroid Institute's mapping services. This extensive historical evidence provided the necessary foundation to submit the findings to the Minor Planet Center.
3Defining Dwarf Planet Characteristics
ED138 is classified as a trans-Neptunian object, orbiting further from the sun than Neptune. Preliminary estimates place its width between 600 and 1,500 kilometers, suggesting sufficient mass for its own gravity to maintain a spherical shape. These physical properties align with the strict criteria required for formal dwarf planet status recognition.
4Distinction From Regular Planets
The primary difference between a dwarf planet and a regular planet lies in orbital clearance. While regular planets possess enough gravitational pull to clear their paths of debris, dwarf planets share their orbits with asteroids and comets. ED138 currently meets this specific definition, as it has not cleared its surrounding orbital space.
5Overcoming Background Noise Challenges
The discovery was difficult because ED138 orbits against the backdrop of the Milky Way. This region is densely crowded with millions of stars, likely masking the object in previous telescope observations. Researchers believe it was captured in older images but remained undetected due to the overwhelming amount of background celestial noise.
6Rubin Observatory Operational Capacity
The Rubin Observatory has significantly accelerated discovery rates, submitting 11,000 new asteroid findings since June 2025. Mario Jurić noted that the facility provides unprecedented speed, depth, and precision in sky exploration. This technological capability allows scientists to re-examine decades of historical imagery to identify objects that were previously overlooked by astronomers.
7Future Implications for Astronomy
The potential confirmation of ED138 would expand the known list of dwarf planets, which currently includes Eris, Ceres, Haumea, Makemake, and Pluto. Pluto was famously downgraded twenty years ago, highlighting the evolving nature of planetary definitions. This discovery serves as a benchmark for the effectiveness of modern automated data processing in space.
8Expanding the Solar Catalog
Holman remains optimistic that ED138 is merely the first of many future discoveries enabled by the Rubin Observatory's advanced scanning techniques. By refining algorithms to filter out background noise, the team expects to uncover more rare celestial bodies. This ongoing research continues to reshape our understanding of the vast, complex solar system.
Original article: CNET — Researchers Identify Potential Sixth Dwarf Planet Candidate ED138