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Astronomers May Have Found Sixth Dwarf Planet Beyond Pluto
Confirmed
In Short: Astronomers can now get to work on learning more about 2026 ED138 to see if it can join the dwarf planet family.
Astronomers using the Vera C. Rubin Observatory may have discovered a new dwarf planet candidate beyond Pluto's orbit. The object, designated 2026 ED138, was spotted in the outer reaches of the solar system.
Further observations are needed to confirm if the object has enough mass to be pulled into a round shape, a key requirement for a dwarf planet.
The International Astronomical Union Minor Planet Center has given the object the provisional designation ED138. If confirmed, it would join the five other known dwarf planets: Pluto, Ceres, Eris, Haumea, and Makemake.
The object's orbit lies within Pluto's range of distances from the Sun, yet it was only recently discovered. It takes around 281 years to complete one orbit of the Sun, coming to a distance of 36.86 astronomical units from the Sun at perihelion and 49.04 astronomical units at aphelion.
Researchers have detected thousands of trans-Neptunian objects, from dwarf planets to small, icy bodies, while comets plunging toward the inner Solar System offer glimpses of material from even more distant regions.
On October 13, 2026, astronomer Scott S. Gaudi was analyzing Rubin observations when something unusual caught his attention. He and his colleague Kevin Napier found 30 more observations of the object by Rubin that dated to between March and July 2026.
The Vera C. Rubin Observatory, with its ability to capture movement and change among a vast number of objects, greatly extends our ability to reveal and understand new things about our solar system.
Astronomers can now get to work on learning more about 2026 ED138 to see if it can join the dwarf planet family.
My first reaction was one of excited disbelief," said Scott S. Gaudi in a statement. "If confirmed as a dwarf planet, ED138 would join a very small family of worlds.
What's confirmed
- Rubin Observatory has spotted 2026 ED138—a large, bright trans-Neptunian object that scientists have identified as a dwarf planet candidate.
- “My first reaction was one of excited disbelief,” Holman said in a statement.
- "Objects like this are very rare, so I immediately started checking whether I or the code had done something wrong." Everything we have managed to learn so far about the Solar System beyond Neptune (about 30 astronomical units from the Sun) indicates that there's a lot more out there than meets the eye.
What's still developing
- Initial measurements indicate that 2026 ED138 has a diameter between 600 and 1,500 kilometers (373 and 932 miles), which makes it one of the largest dwarf planet candidates yet detected.
- For many years, scientists have reconstructed the space beyond Pluto from breadcrumbs – scattered discoveries and indirect clues gleaned from the motion of those objects we have actually detected.
- Researchers have just announced a spectacular new discovery – the telescope's first candidate dwarf planet, a large object in the Kuiper Belt some 600 to 1,500 kilometers (373 to 932 miles) across.
- In trans-Neptunian space lies the Kuiper Belt – a vast field of icy objects that extends out to about 55 astronomical units; and much farther beyond that, the hypothetical Oort Cloud, which may extend tens of thousands of astronomical units into space.
- “Objects like this are very rare, so I immediately started checking whether I or the code had done something wrong.” When Holman and his colleague Mario Jurić of the University of Washington went to double-check, they found 30 more observations of the object by Rubin that dated to between March and July 2026.