Rubin finds a possible sixth dwarf planet beyond Pluto
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Astronomers have found a large icy object beyond Neptune that could become the sixth officially recognised dwarf planet. The object, temporarily called 2026 ED138, was seen in observations from the Simonyi Survey Telescope at the NSF-DOE Vera C. Rubin Observatory, according to ScienceDaily, which reports the team's press conference.
Matthew Holman of the Harvard & Smithsonian Center for Astrophysics made the first detection on the evening of 13 October, using software that looks for moving points of light. Mario Jurić of the University of Washington then found 20 more detections, some from March 2026. Older images from 2016 helped rebuild more than a decade of its orbit.
The team estimates the object is between 600 and 1,500 kilometres across. That range comes from its brightness, its distance of about 46 astronomical units, and an assumption about how much sunlight its surface reflects. Holman and Jurić say more observations are needed before its size is fixed and it is confirmed as a dwarf planet.
Why it matters: Jurić says it is the largest trans-Neptunian object found in about 20 years. It also shows how much the Rubin survey can find in crowded parts of the sky.
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Sources: ScienceDaily