\n The finding is the result of detections made by the Vera C. Rubin Observatory, a new telescope that sits atop a 2,682-meter-tall (8,800-foot-tall) mountain in Chile and houses the world\u2019s largest digital camera. The telescope started operating in 2025 and is capable of imaging the entire sky every three days.\n <\/p>\n
\n Matthew Holman, a Smithsonian senior astrophysicist and lecturer in astronomy at Harvard University, ran a computer program he codeveloped to comb through data collected by Rubin earlier in 2026, scanning billions of detections of moving objects. When ED138 popped up, Holman said he first reacted with \u201cexcited disbelief,\u201d and immediately checked for a false positive or an error with the computer program.\n <\/p>\n
\n To confirm the observation, Holman, who is also a Rubin Operations team member, worked with his colleague Mario Juri\u0107, the Rubin Solar System lead scientist and a professor in the department of astronomy at the University of Washington. Juri\u0107 looked for more observations of ED138 in Rubin\u2019s catalog, and found 20 additional ones dating back to March 2026. Eventually, using other sources, the researchers were able to plot the orbit of the object as far back as 10 years.\n <\/p>\n
\n However, Holman warns, ED138 isn\u2019t officially a dwarf planet yet: \u201cAt this point, it\u2019s still a candidate. We really need to know how physically big it is, and that will take a few months, probably.\u201d\n <\/p>\n
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\n ED138\u2019s diameter is estimated to be between 600 and 1,500 kilometers<\/a> (370 and 930 miles), which would make it bigger than the smallest of the recognized dwarf planets, Ceres. It currently orbits the sun at a distance of about 46 astronomical units \u2014 with each unit representing the average distance between Earth and the sun. That means ED138 is farther away than Pluto and also a trans-Neptunian object, or TNO \u2014 a class of objects that orbit the sun at a distance greater than Neptune\u2019s.\n <\/p>\n \n In the night sky, ED138 is not visible with the naked eye but \u201cis bright enough that really capable amateurs can see it if they know where to look,\u201d according to Holman.\n <\/p>\n \n Part of the reason scientists hadn\u2019t discovered ED138 before is because it\u2019s in the southern hemisphere, and therefore very difficult to observe from the northern hemisphere, Holman noted.\n <\/p>\n \n \u201cThat already rules out whole sets of telescopes that might have found this, and there aren\u2019t as many telescopes searching the sky in the southern hemisphere,\u201d he said.\n <\/p>\n \n Another factor that kept ED138 hidden is that it is on the same plane as our galaxy. \u201cFor the last 20 years, the object has kind of been looping its way across the Milky Way, from our point of view,\u201d Holman explained. \u201cPeople don\u2019t typically search for things in the Milky Way, because there\u2019s so many stars that it\u2019s really hard to find moving objects.\u201d\n <\/p>\n \n The new dwarf planet candidate joins the Rubin telescope\u2019s growing list of detected objects \u2014 largely asteroids<\/a> and much smaller TNOs. According to Holman, there might be \u201ca handful\u201d more objects the size of ED138, and Rubin should eventually find those, too.\n <\/p>\n \n \u201cRubin Observatory is just doing its job really well, inventorying the Solar System to new depths,\u201d said Megan Schwamb, a reader in astrophysics at Queen\u2019s University Belfast and a member of the Rubin Solar System Operations team, in an email.\n <\/p>\n \n \u201cI was surprised that it found such an object so early in the commissioning observations. This was not on my bingo card for this year,\u201d Schwamb added. \u201cIt shows how Rubin\u2019s combination of speed, depth, and sky coverage is going to transform our view of the Solar System over the next decade and especially in the next few years.\u201d\n <\/p>\n ![\"A](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2026\/10\/noirlab2626c.jpg\")
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