Overview
- Researchers using data from the Vera C. Rubin Observatory identified the object 2026 ED138 in late October 2026 after software developed by Matthew Holman flagged a bright moving source in 2026 survey images.
- The discovery team recovered archival detections back to 2016 and dozens of Rubin observations from 2026 to reconstruct an orbit that sits about 46 astronomical units from the Sun with an orbital period near 281 years and an inclination of roughly 25 degrees.
- Initial size estimates place ED138 between about 600 and 1,500 kilometers in diameter, which would make it large enough to be a candidate dwarf planet but not yet officially classified by the International Astronomical Union.
- Astronomers have announced targeted follow up with thermal and infrared facilities, occultation monitoring and searches for satellites over the coming months because those measurements are needed to determine its true size, shape and mass.
- The find highlights Rubin’s wide, deep repeated survey and image‑mining tools and suggests the observatory will substantially grow the known population of outer‑solar‑system worlds in the coming years.