A giant icy object spotted beyond Pluto has scientists buzzing, but they say it's too early to celebrate a new dwarf planet just yet.
Astronomers using the Vera C. Rubin Observatory in Chile have found a large, bright object beyond Pluto called 2026 ED138, and it might become the Solar System's sixth officially recognized dwarf planet. The discovery was announced on October 27, 2026, though researchers caution the object still needs to be confirmed.
How the 2026 ED138 dwarf planet candidate was found
The story starts with the Simonyi Survey Telescope, the powerful instrument at the heart of the Rubin Observatory on Cerro Pachón. Astrophysicist Matthew Holman was the first to notice something odd while digging through the telescope's data on October 13, 2026. The object was far away, yet still bright enough to catch his eye, which hinted it might be unusually large for something living way out past Neptune.
Once Holman flagged it, Rubin scientist Mario Jurić went back through older images to see if the object had shown up before. He found about 20 earlier detections of the same object, with some dating back to March 2026. Those extra sightings let the team map out its orbit and confirm this wasn't some fluke or camera glitch. It was a real, distant world quietly circling the Sun.
Size and distance of the possible new dwarf planet
Right now, scientists think 2026 ED138 measures somewhere between 600 and 1,500 kilometers across, or roughly 370 to 930 miles. That's a huge range, and there's a simple reason for it. A smaller object with a shiny, reflective surface can look just as bright as a bigger object with a dull, dark surface. Until researchers learn more about how much sunlight the object actually reflects, they can't narrow down its true size.
As for location, 2026 ED138 sits about 46 astronomical units from the Sun, which works out to roughly 4.3 to 4.4 billion miles. That puts it well beyond Pluto's average orbit. Its path around the Sun is also tilted compared to where most planets travel, an inclined orbit that scientists find especially interesting because it might hold clues about how the outer Solar System formed billions of years ago.
Why scientists are holding off on official confirmation
Despite the excitement, nobody is ready to call 2026 ED138 a dwarf planet just yet. Rubin Observatory itself described it as a dwarf planet candidate, not a confirmed one. Holman put it plainly, saying, "At this point, it's still a candidate." He added that researchers "really need to know how physically big it is, and that will take a few months, probably."
The National Science Foundation, which helps run the observatory along with the Department of Energy, said preliminary analysis suggests ED138 could be "one of the largest dwarf planet candidates ever found." That's a big deal, but it's also a careful choice of words. Size estimates from brightness alone aren't enough. Scientists need to confirm the object is big enough and round enough, shaped by its own gravity into a roughly spherical form, before it can officially join the dwarf planet club.
What it would take to become the sixth dwarf planet
Right now, the International Astronomical Union recognizes exactly five dwarf planets: Ceres, Pluto, Eris, Haumea, and Makemake. Ceres sits in the asteroid belt between Mars and Jupiter, while the other four live out in the far reaches of the Solar System alongside ED138. This list hasn't changed since 2006, the same year Pluto got bumped down from full planet status because it shares its orbital neighborhood with too many other icy bodies.
For 2026 ED138 to join that group, it needs to meet three basic conditions. It has to orbit the Sun, which it clearly does. Its gravity needs to be strong enough to pull it into a roughly round shape. And it needs to fail at clearing its orbital path of other debris, similar to how Pluto shares its space with countless other Kuiper Belt objects. The first condition is already satisfied. The other two depend entirely on getting a clearer picture of its actual size and mass, which is exactly what astronomers are working on now.
What comes next for the outer Solar System discovery
Over the coming months, researchers plan to gather more observations to pin down ED138's orbit, brightness, and physical makeup. The goal is simple: shrink that huge 600-to-1,500-kilometer size range down to something much more precise. Once that happens, scientists will have a much better idea of whether this distant world truly belongs alongside Pluto and the four other dwarf planets.
The discovery also shows off what the Rubin Observatory was built to do. Its wide-field camera can scan huge chunks of sky repeatedly, which makes it unusually good at catching faint, slow-moving objects that shorter observation campaigns might miss entirely. If ED138 does eventually earn official recognition, it will get a permanent name to replace its current provisional label. Until then, calling it a possible sixth dwarf planet is the most accurate way to describe what scientists have found so far.
