The icy object could join the solar system’s recognized dwarf planets
Astronomers have discovered a large icy object beyond Pluto that could qualify as a dwarf planet, potentially adding a new member to the solar system’s officially recognized group.
The discovery was announced on Thursday by the US-funded Vera C. Rubin Observatory in Chile, which houses the world’s largest 3.2-gigapixel digital camera, built specifically for astronomy.
Researchers estimate that the object, provisionally named 2026 ED138, is between 600 and 1,500 km in diameter and may be one of the largest dwarf planet candidates ever found. It currently sits roughly 46 times farther from the Sun than Earth. Pluto’s average distance, for comparison, is about 40 times Earth’s.
The object likely escaped detection until now because it appeared against a crowded backdrop of millions of stars near the plane of the Milky Way. However, Rubin’s repeated images and tracking software has now allowed scientists to pick out its movement.
#ICYMI: our Solar System has a newly-discovered dwarf planet candidate! Meet 2026 ED138, recently revealed by NSF–DOE Rubin Observatory ☄
Let’s get to know this new world a little bit, shall we?
If confirmed, ED138 would join five dwarf planets recognized by the International Astronomical Union, which include Eris, Haumea, Makemake, Ceres, and Pluto, which was considered the solar system’s ninth planet until it was reclassified in 2006. Dwarf planets orbit the Sun and have enough gravity to become roughly round, but share their orbital neighborhoods with other bodies.
ED138 may be large enough to meet the roundness requirement, but astronomers still need more research and better measurements before determining its status.
“The main thing we need to do is to establish the physical size of 2026 ED138,” discoverer Matt Holman, an astrophysicist at the Center for Astrophysics, Harvard and Smithsonian, told Reuters. He explained that ED138’s size is currently estimated from the sunlight it reflects. However, a small shiny object can appear just as bright as a large, dark one, Holman said.
To narrow down the true size of the object, researchers could use Chile’s ALMA telescope which can detect radiation emitted by ED138 itself, helping get a more accurate measurement.
The last dwarf planet officially recognized by the International Astronomical Union was Haumea in 2008. Other candidates have since emerged, including 2017 OF201, whose discovery was announced in May 2025, but none have yet been formally added to the list.
