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<\/a><\/figure>\n\n\n\nIn the outer reaches of our Solar System, beyond the orbit of Pluto, NSF\u2013DOE Vera C. Rubin Observatory has spotted 2026 ED138 \u2014 a large, bright trans-Neptunian object that scientists have identified as a dwarf planet candidate. The observations were announced today by the International Astronomical Union Minor Planet Center (MPC). If confirmed, ED138 would be among the largest dwarf planets ever discovered in this region of the Solar System.<\/p>\n\n\n\n
With observations taken during the run up to the Legacy Survey of Space and Time (LSST<\/a>), NSF\u2013DOE Vera C. Rubin Observatory<\/a> has discovered a new dwarf planet<\/a> candidate in our Solar System. The candidate, which has been given the provisional designation 2026 ED138 (ED138), was found by Rubin Operations team member and in-Kind contributor Matthew Holman (Center for Astrophysics | Harvard & Smithsonian [CfA]). He contributes to improving Rubin’s algorithms that search for distant moving objects in our Solar System. The candidate\u2019s distance from the Sun places it beyond the orbit of dwarf planet Pluto. Initial analysis indicates that it may be among the largest and brightest bodies scientists have discovered in this region of the Solar System.<\/p>\n\n\n\n Rubin Observatory is jointly funded by the U.S. National Science Foundation and the U.S. Department of Energy’s Office of Science.<\/p>\n\n\n\n \u201cRubin Observatory’s super power is the ability to clearly capture movement and change among a vast number of objects and phenomena that humans have never seen before,\u201d<\/em> says Edward Ajhar, NSF Program Director for Rubin Observatory. \u201cThat power greatly extends our ability to reveal and understand new things about our Solar System, the Milky Way, and billions of other galaxies across the Universe.\u201d<\/em><\/p>\n\n\n\n \u201cRubin Observatory\u2019s unique strengths make it an incredible tool for investigating a wide range of astrophysical phenomena, from dark energy to the discovery of this dwarf planet candidate,\u201d<\/em> says Kathy Turner, DOE\u2019s Program Manager for Rubin Observatory.<\/p>\n\n\n\n Today, MPC announced<\/a> the discovery in a Minor Planet Electronic Circular. Mario Juri\u0107, faculty at the University of Washington and Rubin Solar System Lead Scientist, and Holman presented the results at a press conference at the 58th Annual Division for Planetary Sciences (DPS<\/a>) meeting in Spokane, Washington.<\/p>\n\n\n\n On the evening of 13 October, Holman was running data collected by Rubin earlier in 2026 through a search code he developed with CfA colleague Kevin Napier. The code is built to look at billions of detections of moving objects, compare them, and find the detections that correspond to the same object. Using this method, Holman uncovered ED138, and he immediately noticed that its brightness and distance indicated that it is unusually large.<\/p>\n\n\n\n \u201cMy first reaction was one of excited disbelief,\u201d<\/em> says Holman. \u201cObjects like this are very rare, so I immediately started checking whether I or the code had done something wrong.\u201d<\/em><\/p>\n\n\n\n To remove any doubt, a detailed search through the data began in the hopes of uncovering more observations of ED138. Juri\u0107 searched Rubin\u2019s catalogs and images and found 20 more observations, going back to 4 March 2026. In all, Rubin’s Simonyi Survey Telescope observed ED138 30 times on 20 nights between 4 March and 11 July. Additional archival images from the DOE-fabricated Dark Energy Camera (DECam<\/a>), and uncovered by the Asteroid Institute\u2019s<\/a> ADAM Precovery service<\/a>, provided data going all the way back to 2016. These data allowed the team to trace more than 10 years of ED138’s orbit. DECam is mounted on the NSF Victor M. Blanco 4-meter Telescope<\/a> at Cerro Tololo Inter-American Observatory (CTIO<\/a>), a Program of NSF NOIRLab.<\/p>\n\n\n\n ED138 is currently at a distance of about 46 astronomical units (au<\/a>), where 1 au is the average distance between the Earth and the Sun. For reference, dwarf planet Pluto has an average distance of 40 au. This classifies ED138 as a trans-Neptunian object (TNO<\/a>) \u2014 objects that orbit the Sun at a distance greater than Neptune\u2019s.<\/p>\n\n\n\n A model of the Solar System showing the orbital pathway of newly discovered dwarf planet candidate 2026 ED<\/em>138<\/em> (ED138). ED138 was discovered in observational data from NSF\u2013DOE Vera C. Rubin Observatory spanning 4 March\u201311 July 2026. The rendering starts on 8 May 2026. Visit <\/em>Orbitviewer<\/em><\/a> to interact with ED138\u2019s orbit in 3D and in real-time. Credit: NSF\u2013DOE Vera C. Rubin Observatory\/NOIRLab\/SLAC\/AURA\/R. Proctor.<\/em><\/p>\n\n\n\n Scientists study the size, composition, and orbital trajectories of TNOs to understand how the Solar System formed, how the giant planets migrated over time, and how smaller objects have been scattered throughout this evolution. ED138\u2019s orbit is tilted almost 25 degrees<\/a> off of the plane of the Solar System, classifying it as a hot-classical TNO<\/a> and suggesting that it was disturbed from its original orbit through gravitational interactions with Neptune.<\/p>\n\n\n\n Not all TNOs are considered dwarf planet candidates, with the distinction being in the size and shape of the object. To be a dwarf planet an object needs to be massive enough for its own gravity to pull it into a round shape. Based on ED138\u2019s distance, brightness and estimated surface reflectivity (albedo), the team estimates that its size is between 600 and 1500 kilometers, and icy bodies this large are expected to be round.<\/p>\n\n\n\n This preliminary analysis places ED138 among the largest dwarf planet candidates<\/a> ever discovered beyond Neptune, though observations in the infrared are needed to constrain its exact size and confirm its nature as a dwarf planet. If confirmed, ED138 would join the five dwarf planets recognized by the International Astronomical Union (IAU<\/a>): Pluto, Ceres, Eris, Haumea, and Makemake.<\/p>\n\n\n\n ED138 was found in a region of sky close to the plane of the Milky Way \u2014 a crowded region filled with millions of stars. To most telescopes, ED138 has been lost among the myriad background sources, which is likely why it was not discovered until now. Rubin Observatory\u2019s regular and continuous monitoring of the entire Southern Hemisphere sky, combined with powerful algorithms that sift through millions to billions of points of light to identify those corresponding to small moving objects, enabled the team to spot ED138 within the crowded field.<\/p>\n\n\n\n \u201cRubin is giving us an unprecedented capacity to explore the sky through a combination of speed, depth, and precision,\u201d<\/em> says Juri\u0107. \u201cAnd the discovery is just the beginning: once we identify a new object, we can search back months, and sometimes even decades, finding it in images where nobody knew to look. This ability to both discover and \u2018precover\u2019 objects is transforming how quickly and accurately we can determine their orbits and understand the distant Solar System.\u201d<\/em><\/p>\n\n\n\n ED138 joins the rapidly growing sample of Solar System objects discovered by Rubin since it began collecting early data in preparation for the LSST, which began in June 2026. In April, before LSST formally began, the Rubin Solar System team submitted observations of over 11,000 new asteroids<\/a> to the IAU Minor Planet Center (MPC<\/a>), which included roughly 380 new TNOs. At the time, the team called this large submission \u201cthe tip of the iceberg\u201d and expressed their excitement for the discoveries to come once LSST began. With the discovery of ED138, those hopes are coming to fruition.<\/p>\n\n\n\n \u201cIf confirmed as a dwarf planet, ED138 would join a very small family of worlds,\u201d<\/em> says Holman. \u201cRubin will image the whole southern sky again and again for ten years, so any others hiding in the places earlier surveys skipped are now within reach.\u201d<\/em><\/p>\n\n\n\n Now that Rubin has identified ED138, scientists around the globe can organize follow-up observations to uncover even more information about its nature. Images of ED138 are made available to Rubin data rights holders on the Rubin Science Platform<\/a>, an online, web-based environment where scientists can access, explore, and process the massive amounts of data being produced by the LSST. The public can also interact with this discovery on Orbitviewer<\/a>, an interactive web-based app that provides an intuitive way to explore the structure of our cosmic backyard in three dimensions and in real time.<\/p>\n","protected":false},"excerpt":{"rendered":" Ny dv\u00e4rgplanet uppt\u00e4ckt: Vera Rubin-teleskopet levererar redan I g\u00e5r (27.10) meddelade Vera Ruben-ansvariga den f\u00f6rsta st\u00f6rre uppt\u00e4ckten – en sannolik dv\u00e4rgplanet p\u00e5 ett avst\u00e5nd av 46 astronomiska enheter ut i den kalla postneptuniska rymden. Jag k\u00f6r pressrelisen fr\u00e5n observatoriet p\u00e5 engelska. Be my guest! In the outer reaches of our Solar System, beyond the orbit… L\u00e4s mer »Nr 46 2026<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"rop_custom_images_group":[],"rop_custom_messages_group":[],"rop_publish_now":"initial","rop_publish_now_accounts":[],"rop_publish_now_history":[],"rop_publish_now_status":"pending","neve_meta_sidebar":"","neve_meta_container":"","neve_meta_enable_content_width":"","neve_meta_content_width":0,"neve_meta_title_alignment":"","neve_meta_author_avatar":"","neve_post_elements_order":"","neve_meta_disable_header":"","neve_meta_disable_footer":"","neve_meta_disable_title":"","footnotes":""},"categories":[3],"tags":[],"_links":{"self":[{"href":"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-json\/wp\/v2\/posts\/99738"}],"collection":[{"href":"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-json\/wp\/v2\/comments?post=99738"}],"version-history":[{"count":7,"href":"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-json\/wp\/v2\/posts\/99738\/revisions"}],"predecessor-version":[{"id":99748,"href":"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-json\/wp\/v2\/posts\/99738\/revisions\/99748"}],"wp:attachment":[{"href":"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-json\/wp\/v2\/media?parent=99738"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-json\/wp\/v2\/categories?post=99738"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.astb.se\/cassiopeiabloggen\/wp-json\/wp\/v2\/tags?post=99738"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}<\/figure>\n\n\n\n