Vera Rubin Observatory Detects Potential New Dwarf Planet Beyond Neptune

The Vera Rubin Observatory in Chile has detected an icy object, designated 2026 ED138, orbiting the Sun beyond Neptune. Based on its brightness and estimated diameter of 600 to 1,500 km, scientists say the body is likely large enough for its gravity to shape it into a sphere, a key criterion for dwarf-planet status.

The discovery was made by astronomer Matthew Holman of the Center for Astrophysics | Harvard & Smithsonian, who identified the object while processing Rubin data with a search algorithm developed with colleague Kevin Napier. Holman said, "> My first reaction was one of excited disbelief. Objects like this are very rare, so I immediately started checking whether I or the code had done something wrong."

Rubin, which began its Legacy Survey of Space and Time (LSST) in June 2025, repeatedly imaged the object—30 detections on 20 nights between March and July of this year. Earlier observations from the Dark Energy Camera at the Víctor M. Blanco Telescope also recorded the object as far back as 2016.

The object's orbit is inclined about 25 degrees to the ecliptic, suggesting a past gravitational interaction with Neptune that altered its trajectory. Currently, 2026 ED138 resides roughly 46 astronomical units from the Sun, farther than Pluto's average distance.

Confirming its status as a dwarf planet will require precise size measurements, likely through infrared observations with NASA's James Webb Space Telescope. Holman added, "> If confirmed as a dwarf planet, ED138 would join a very small family of worlds. Rubin will image the whole southern sky again and again for 10 years, so any others hiding in the places earlier surveys skipped are now within reach."

The finding highlights Rubin's capability to expand the solar-system inventory and may lead to the identification of additional distant dwarf planets over the survey's decade-long operation.