Rubin Telescope Finds Possible Dwarf Planet Beyond Pluto — What 2026 ED138 Could Reveal

October 29, 2026. A distant, icy body beyond Pluto is emerging as one of the solar system’s most intriguing newly identified objects. The NSF–DOE Vera C. Rubin Observatory announced on October 27 that observations have revealed 2026 ED138, a large trans-Neptunian object that may qualify as a dwarf planet. Its status has not yet been confirmed.

How big is the candidate?

Researchers estimate that ED138 is 600–1,500 kilometers (370–930 miles) across. That is a broad estimate, not a direct diameter measurement: the object’s brightness and distance are known more confidently than the reflectivity of its surface. A darker body would have to be larger to produce the same observed brightness, while a more reflective body could be smaller.

According to the US National Science Foundation and Stanford’s account of the discovery, ED138 is currently roughly 46 astronomical units from the Sun — about 46 times the Earth–Sun distance. Its orbit is inclined by nearly 25 degrees relative to the solar system’s main plane, a clue to the gravitational history of distant icy objects.

Why astronomers missed it

ED138 sits against a crowded part of the Milky Way sky, where distinguishing a faint moving object from numerous background stars is difficult. Rubin’s repeated observations and automated searches made that distinction possible. Matthew Holman identified the candidate while analyzing data on October 13; researchers subsequently found earlier images, including archival observations from 2016, to help constrain its orbit.

That process is important in its own right. Repeated wide-field surveys can turn a faint, easily overlooked dot into an object with a trackable orbit, while archived images can extend its observation history by years. It is an early demonstration of how Rubin’s long-term survey could expand the census of the outer solar system.

What remains unproven

A dwarf planet must be sufficiently massive for its gravity to produce a nearly rounded shape. ED138 is large enough to be a plausible candidate, but scientists still need further observations — including at infrared wavelengths — to refine its diameter and physical properties. It would be inaccurate to call ED138 the solar system’s confirmed sixth dwarf planet today. The five currently recognized by the International Astronomical Union are Ceres, Pluto, Haumea, Makemake and Eris.

See the observatory’s official orbital animation

The following is a scientific orbital visualization, not actual camera footage of ED138. It is linked by the NSF’s October 27 announcement and shows a model of the candidate’s orbit.

Official NSF announcement and its embedded video | Rubin Observatory’s credited orbital animation page. The official animation is credited to NSF–DOE Vera C. Rubin Observatory/NOIRLab/SLAC/AURA/R. Proctor, with orbital data from the IAU Minor Planet Center and additional sky-map credits on the source page. Embedded player playback has not been independently tested.

Featured image: illustrative Milky Way photograph by Renden Yoder / Unsplash; it is not a photograph of ED138.

Primary reporting and verification: Rubin Observatory, October 27; NSF, October 27; Reuters, October 28.

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