Icy Object 2026 ED138 Identified Beyond Pluto, May Qualify as Dwarf Planet
Astronomers using Chile's Vera C. Rubin Observatory have detected a distant icy body, 2026 ED138, whose size could place it among the solar system's recognized dwarf planets, pending further observations.
Astronomers have detected an icy object designated 2026 ED138 orbiting beyond Pluto, using the Vera C. Rubin Observatory in Chile. The body is estimated to be between 600 and 1,500 kilometres in diameter and lies roughly 46 astronomical units from the Sun, farther than Pluto's average distance of about 40 astronomical units.
If subsequent measurements confirm its size and shape, 2026 ED138 could join the five dwarf planets currently recognized by the International Astronomical Union—Pluto, Eris, Haumea, Makemake and Ceres. The International Astronomical Union defines a dwarf planet as a body that has sufficient mass for its gravity to shape it into a round form.
"For me, what this demonstrates is that many exciting discoveries remain to be made with the Rubin Observatory and other telescopes," said astrophysicist Matt Holman of the Center for Astrophysics, Harvard & Smithsonian, who first identified the object.
Holman added that determining the object's precise dimensions is the next priority, noting that observations at longer wavelengths, such as those possible with the Atacama Large Millimeter/submillimeter Array (ALMA), can help measure the object's own emitted light rather than reflected sunlight.
The discovery was presented at a scientific meeting in Spokane, Washington, and researchers plan additional observations to confirm whether 2026 ED138 meets the criteria for dwarf-planet status.