Giant New Dwarf Planet Candidate Discovered in Our Solar System
The object, named 2026 ED138, was found hiding in the Kuiper Belt and may rival the size of other known dwarf planets.
Scientists have announced the discovery of a large object in the Kuiper Belt, a region of icy bodies beyond Neptune, that is a strong candidate for a new dwarf planet. Named 2026 ED138, its entire orbit lies within Pluto's distance range from the Sun, yet it has only recently been detected.
The discovery was made using data from the Vera C. Rubin Observatory in Chile, which is equipped with the largest digital camera ever built for astronomy. The observatory began operations in June 2025, and 2026 ED138 entered its field of view by March 2026. The team has since traced the object through 30 detections across 20 nights of observations between March 4 and July 11, 2026.
If 2026 ED138 is indeed a dwarf planet, it could rival the size of other well-known dwarf planets such as Makemake and Haumea. Its discovery highlights the capabilities of the Rubin Observatory in scanning vast areas of the sky and identifying faint, slow-moving bodies that might have been missed by previous surveys.
Astrophysicist Matthew Holman of the Harvard-Smithsonian Center first spotted the object on October 13, 2026, while analyzing Rubin observations. Further investigation of older data from the Dark Energy Camera revealed the object in images dating back to February 2016, with additional sightings in 2017, 2018, 2019, and 2023. Holman expressed surprise at the rarity of such discoveries and meticulously double-checked his findings.
The Kuiper Belt, where 2026 ED138 resides, extends from approximately 30 to 55 astronomical units (AU) from the Sun. The region beyond the Kuiper Belt is the theoretical Oort Cloud. Detecting objects in these distant regions is exceptionally challenging due to their faintness, the minimal sunlight they reflect, and the little heat radiation they emit.
2026 ED138 orbits the Sun approximately every 281 years, with its distance from the Sun varying between 36.86 AU and 49.04 AU. Its orbit is also tilted by about 24.5 degrees relative to the ecliptic plane, the common orbital plane of most planets. This significant tilt means the object spends much of its time above or below the traditional viewing zones of most telescopes, contributing to its late discovery.
Researchers are now working to understand the cause of these unusual orbital characteristics, which could be influenced by a large planet or a collection of smaller bodies. Holman indicated that the Rubin Observatory's ongoing and repeated scans of the entire southern sky will increase the chances of finding other objects that have similarly evaded detection in less-surveyed areas.