“Objects like this are very rare, so I immediately started checking whether I or the code had done something wrong.”<\/p>\n
Everything we have managed to learn so far about the Solar System beyond Neptune (about 30 astronomical units<\/a> from the Sun) indicates that there’s a lot more out there than meets the eye.<\/p>\n In trans-Neptunian space lies the Kuiper Belt \u2013 a vast field of icy objects that extends out to about 55 astronomical units; and much farther beyond that, the hypothetical Oort Cloud, which may extend tens of thousands of astronomical units into space.<\/p>\n We’ve detected thousands of trans-Neptunian objects, from dwarf planets to small, icy bodies, while comets plunging toward the inner Solar System offer glimpses of material from even more distant regions.<\/p>\n However, directly observing the objects out there is extraordinarily difficult.<\/p>\n At such enormous distances from the Sun, they receive very little sunlight to reflect, making them extremely faint at optical wavelengths. They’re also bitterly cold, emitting only a feeble thermal glow in the far infrared.<\/p>\n And they’re not stationary. As they travel around the Sun, their positions against the background stars gradually change. Unless a telescope is looking in the right place at the right time, an object can easily escape detection.<\/p>\n The final nail in the coffin is orbital misbehavior. The larger objects closer to the Sun orbit more or less in a flat plane \u2013 but beyond Neptune, things can get more chaotic. Many trans-Neptunian objects orbit the Sun at weird angles, dramatically expanding the area of sky astronomers need to search.<\/p>\n This is where the Vera C. Rubin Observatory comes in.<\/p>\n Equipped with the largest digital camera<\/a> ever built for astronomy, Rubin is designed to repeatedly survey enormous swathes of the southern sky, capturing objects too faint for many previous surveys to detect.<\/p>\n Rubin’s 3.2-gigapixel camera can image an area of sky equivalent to around 40 full moons<\/a> in a single exposure. <\/p>\n By returning to the same regions again and again, astronomers can identify faint points of light that change position against the background stars, revealing objects moving through the Solar System.<\/p>\n It saw first light in June 2025<\/a> \u2013 and by March 2026, ED138 had wandered into its field of view.<\/p>\n On 13 October 2026, Holman was analyzing Rubin observations using software developed with colleague Kevin Napier when something unusual caught his attention.<\/p>\n The telescope had recorded a large, previously unknown object moving through the Kuiper Belt.<\/p>\n The team traced it through 30 detections across 20 nights of Rubin observations, dating from 4 March to 11 July 2026.<\/p>\n Then, they looked further back \u2013 and found the object hiding in archival observations from the Dark Energy Camera, dating all the way back to February 2016.<\/p>\n For a decade, evidence of this distant world had been sitting in astronomical images, just waiting for someone to come along and find it.<\/p>\n And it wasn’t limited to just one observation. The Dark Energy Camera had also snapped the object<\/a> in 2017, 2018, 2019, and 2023.<\/p>\n Those archival observations were a gift \u2013 extending the observational record back years and allowing the researchers to characterize ED138’s orbit.<\/p>\n According to the Minor Planet Center<\/a>, ED138 takes around 281 years to complete one orbit of the Sun, coming to a distance of 36.86 astronomical units from the Sun at perihelion and 49.04 astronomical units at aphelion.<\/p>\n Pluto, for context, orbits between 29.6 and 49.08 astronomical units<\/a> from the Sun. ED138’s average orbital distance is around 42.95 astronomical units, slightly farther out than Pluto’s, due to its more distant perihelion.<\/p>\n Since ED138 hangs out in Pluto’s range, you might be wondering how it has evaded astronomers.<\/p>\n Well, its orbit is also tilted by around 24.5 degrees relative to the plane of the Solar System \u2013 a striking example of the orbital shenanigans that can make trans-Neptunian objects so difficult to find.<\/p>\n To make matters worse, ED138 was hiding against the densely populated backdrop of the Milky Way, where myriad stars made it even harder to pick out.<\/p>\n The object’s exact size, however, remains a mystery.<\/p>\n Astronomers can estimate its diameter from its brightness and distance, but there’s a catch. A smaller object with a highly reflective, icy surface can appear just as bright as a much larger object with a darker surface.<\/p>\n Without knowing how reflective ED138 is, researchers can only estimate that it measures somewhere between 600 and 1,500 kilometers across.<\/p>\n At those dimensions, however, it’s likely to be massive enough for its own gravity to pull it into a roughly spherical shape \u2013 one of the defining characteristics of a dwarf planet.<\/p>\n Further observations, particularly at infrared wavelengths, will help astronomers pin down its size and assess whether it meets the criteria for dwarf planet status \u2013 whereupon, no doubt, it will be given a catchier name than ED138.<\/p>\n And ED138 is likely just the beginning.<\/p>\n Over the decade-long survey it commenced in June 2026, Rubin is expected to discover thousands of previously unknown objects in the outer Solar System, helping astronomers piece together its history and evolution \u2013 and perhaps even revealing worlds larger and stranger than anything we’ve found so far.<\/p>\n Among the tantalizing possibilities is the hypothetical Planet Nine, a massive but undiscovered world whose gravitational influence has been proposed to explain the unusual orbits of some distant trans-Neptunian objects.<\/p>\n Rubin could be the thing that lifts the curtain on the Planet Nine mystery \u2013 revealing whether those strange orbits are indeed caused by a prodigal planet or a swarm of rocks in a planet-shaped trenchcoat<\/a>.<\/p>\n Either way, we’re poised for a bold new era of Solar System discovery.<\/p>\n “Rubin will image the whole southern sky again and again for ten years,” Holman says<\/a>, “so any others hiding in the places earlier surveys skipped are now within reach.”<\/p>\n This article was fact-checked by Rebecca Dyer<\/a> and edited by Rebecca Dyer<\/a>. While we pride ourselves on our process, we are only human. If you spot a mistake, please let us know<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"The far reaches of the Solar System are largely a mystery to humanity. This region represents a sort…\n","protected":false},"author":2,"featured_media":897610,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[48],"tags":[1352,79,193],"class_list":["post-897609","post","type-post","status-publish","format-standard","has-post-thumbnail","category-space","tag-msft-content","tag-science","tag-space"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/897609","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/comments?post=897609"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/897609\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media\/897610"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media?parent=897609"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/categories?post=897609"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/tags?post=897609"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"Astronomers](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2026\/10\/discovery.png\")
A mosaic of Rubin’s ED138 discovery images. (NSF\u2013DOE Vera C. Rubin Observatory\/NOIRLab\/SLAC\/AURA; Image Processing: M. Juri\u0107\/UW, D. de Martin & M. Zamani\/NSF NOIRLab<\/a>)<\/p>\n![\"YouTube](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2026\/10\/1793197692_759_0.jpg\")
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