A scientist working on data gathered by the Rubin Observatory has found a strong candidate for our solar system’s sixth known dwarf planet. The Observatory is run by the USA’s National Science Foundation and Department of Energy, who built it on a remote hilltop in Chile and equipped it with the 3200-megapixel Legacy Survey of Space and Time (LSST) Camera, which came online in June 2026. As explained in a Tuesday announcement , Rubin Operations team member and project contributor Matthew Holman, of the Center for Astrophysics (CfA) at Harvard & Smithsonian, used search code he developed with CfA colleague Kevin Napier to analyze data captured before LSST operations commenced. The Observatory says Holman’s and Napier’s code “is built to look at billions of detections of moving objects, compare them, and find the detections that correspond to the same object.” On October 13, the code spotted an object so bright and distant that it is likely unusually large. “My first reaction was one of excited disbelief,” Holman said. “Objects like this are very rare, so I immediately started checking whether I or the code had done something wrong.” Other astroboffins sprang into action, dug into other records, and soon found ten years’ worth of relevant data. Once they all checked their sums, the Minor Planet Center reviewed their work and announced the discovery of the romantically named 2026 ED138 and published lots of data about its orbit, which is at around 46 astronomical units (au)…