Rubin Observatory Finds 1,000-km 2026 ED138 Beyond Pluto, a Possible Sixth Dwarf Planet
Updated
Updated · Gizmodo · Oct 28
Rubin Observatory Finds 1,000-km 2026 ED138 Beyond Pluto, a Possible Sixth Dwarf Planet
3 articles · Updated · Gizmodo · Oct 28
Summary
Four months into its 10-year sky survey, Rubin Observatory has uncovered 2026 ED138, a bright icy body about 46 astronomical units from the Sun and potentially the solar system’s sixth dwarf planet.
Matthew Holman flagged the object in Rubin data using software built to match billions of moving-light detections, and its unusual brightness and distance quickly suggested an unusually large trans-Neptunian object.
20 additional Rubin observations reaching back to March, plus archival images from other surveys dating to 2016, let researchers pin down ED138’s orbit and classify it as beyond Pluto’s average 40-au path.
Estimated at 600 to 1,500 kilometers wide—roughly 1,000 kilometers across—ED138 could be massive enough to become round under its own gravity, though more observations are needed to confirm dwarf-planet status.
The find is the largest trans-Neptunian object discovered in about 20 years and highlights Rubin’s ability to spot rare objects hidden in crowded Milky Way star fields.