Rubin’s dwarf-planet candidate
Size awaits infrared confirmation.
- Event / announcement date
- 2026-10-27
Rubin Observatory announced 2026 ED138 on October 27. Brightness and assumed reflectivity suggest a diameter of 600–1,500 kilometers; infrared observations are still needed to constrain size and confirm its dwarf-planet status. [1]
The Minor Planet Center circular lists measurements from 2016 through July 2026, including older DECam images and new Rubin detections. That extended time baseline supports the published orbit. Its table gives a roughly 281-year orbital period; the provisional designation records the object, rather than certifying its shape. [2]
Linking faint moving detections against a crowded stellar background enabled the discovery. Rechecking archival images then expanded its history. An accurately traced orbit and a confirmed physical size answer different questions. [1]
The source
- Rubin Observatory: ED138 discovery ↗
Source date 2026-10-27 · reviewed October 29, 2026 · October 27 announcement. - Minor Planet Center: Discovery circular ↗
Source date 2026-10-27 · reviewed October 29, 2026 · October 27 orbital record.
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