Astronomers spot a possible new dwarf planet beyond Pluto that hid among the stars until a Chilean telescope found it
Candidate dwarf planet 2026 ED138 orbits roughly 46 times farther from the Sun than Earth and could become only the sixth dwarf planet recognised by the International Astronomical Union.
Smithsonian senior astrophysicist Matthew Holman first reacted with "excited disbelief" when a computer program he co-developed flagged the object — designated 2026 ED138 — while scanning billions of detections from the Vera C. Rubin Observatory earlier this year. ED138 orbits roughly 46 times farther from the Sun than Earth, with a diameter thought to fall somewhere between 600 and 1,500 kilometres. Holman then worked with University of Washington professor Mario Jurić, who found 20 additional observations in Rubin's catalogue, allowing the team to plot the object's orbit as far back as 2016.
ED138 went undetected for so long because it lies against a heavily crowded stellar field, making it nearly indistinguishable from the background stars surrounding it.
If confirmed, it would become only the sixth dwarf planet recognised by the International Astronomical Union, joining Pluto, Eris, Haumea, Makemake and Ceres.
Holman cautions it is still a candidate: 'We really need to know how physically big it is, and that will take a few months.'
