New Dwarf Planet Candidate Found Beyond Pluto: 2026 ED138
A new dwarf planet candidate, designated 2026 ED138, has been spotted beyond Pluto by the Vera C. Rubin Observatory, possibly the solar system's sixth. Here is how big it is, how far out it orbits, why it is still only a candidate, and what it means that Rubin found it in its first months of work.
Astronomers using the Vera C. Rubin Observatory have identified a new dwarf planet candidate, designated 2026 ED138, orbiting far beyond Pluto. Early estimates put it at roughly 600 to 1,500 kilometres across, currently about 46 astronomical units from the Sun on an orbit of around 282 years. If confirmed, it would be the solar system's sixth officially recognised dwarf planet and one of the most significant such finds in about twenty years. It is still only a candidate: the International Astronomical Union has to confirm it, and its true size needs follow-up observation. The find is an early sign of what Rubin's decade-long sky survey is expected to deliver, with thousands more distant objects likely to follow. Here is what is known and what still needs checking.
The outer solar system is still mostly unexplored territory, and the newest telescope built to map it has already turned up something big. Astronomers using the Vera C. Rubin Observatory in Chile have flagged a new dwarf planet candidate, catalogued as 2026 ED138, orbiting far beyond Pluto. If it holds up to scrutiny, it would be the sixth dwarf planet officially recognised in our solar system, and a preview of how much the outer dark still hides.
What is 2026 ED138?
2026 ED138 is a large, distant object discovered beyond the orbit of Neptune, in the cold, sparsely populated outer reaches of the solar system. It is what astronomers call a trans-Neptunian object, and it is big enough that it may qualify as a dwarf planet, a world massive enough for its own gravity to pull it into a round shape, but not dominant enough to have cleared its orbital neighbourhood of other debris.
The crucial word is candidate. Being spotted and having an orbit estimated is the start of the process, not the end. Formal recognition as a dwarf planet is a separate step, and its headline properties are still first estimates.
How big is 2026 ED138, and how far away?
The early figures sketch a substantial but distant world:
- Size: roughly 600 to 1,500 kilometres across. That is a wide range because the object's brightness alone does not pin down its size; a smaller, more reflective body and a larger, darker one can look the same from here. Narrowing it needs follow-up measurement, ideally in the infrared.
- Distance: currently about 46 astronomical units from the Sun (one astronomical unit is the Earth-Sun distance), near the far end of its path. Its orbit averages roughly 43 au, still well beyond Pluto, which averages about 39.
- Orbit: a period of around 282 years to circle the Sun once, on a tilted, elongated path typical of the outer solar system.
These are provisional. Expect the numbers, especially the size, to be refined as more observations come in.
How did the Rubin Observatory find it?
The Vera C. Rubin Observatory is purpose-built for exactly this. Its Legacy Survey of Space and Time (LSST) repeatedly photographs the entire visible southern sky, and software compares those images night after night to flag anything that moves or changes. A faint, slowly drifting point of light against the fixed stars is the signature of a distant solar-system body, and that is how 2026 ED138 surfaced. Archival images from earlier years can then be searched for the same object, extending its observed track backwards and tightening the orbit. The find was announced on 27 October 2026, after astronomer Matthew Holman and colleagues identified the object in Rubin's data; Mario Jurić, who leads Rubin's solar-system work, called it the largest trans-Neptunian object found in about twenty years.
Finding a probable dwarf planet this early is notable because Rubin has only recently begun full science operations. It is less a lucky catch than a demonstration of the instrument's reach.
Could this be the solar system's sixth dwarf planet?
Possibly, and that is the honest answer. There are currently five officially recognised dwarf planets. For a table at a glance:
| Dwarf planet | Location | Approx. diameter | Recognised |
|---|---|---|---|
| Ceres | Asteroid belt | ~940 km | 2006 |
| Pluto | Kuiper Belt | ~2,377 km | 2006 |
| Eris | Scattered disc | ~2,326 km | 2006 |
| Haumea | Kuiper Belt | ~1,560 km | 2008 |
| Makemake | Kuiper Belt | ~1,430 km | 2008 |
| 2026 ED138 | Beyond Neptune (candidate) | ~600-1,500 km (est.) | Not yet |
Whether 2026 ED138 joins that list depends on confirming it is massive enough to be rounded by its own gravity, which is why the size estimate matters so much, and on review by the International Astronomical Union, the body that rules on these classifications. Until then it is a strong candidate, not a member.
Is 2026 ED138 Planet Nine?
No, and it is worth separating the two ideas because they get conflated. Planet Nine (sometimes Planet X) is a hypothetical large planet proposed to explain the clustered orbits of some distant objects; it has never been directly observed. 2026 ED138 is the opposite: a real object that has actually been seen and tracked, but far too small to be a major planet. Finding more distant worlds like it is exactly how astronomers hope to eventually settle the Planet Nine question, by mapping the outer solar system densely enough to see whether an unseen planet is really tugging on anything.
What happens next?
Two things. First, confirmation: more observations to pin down the size and orbit, and a formal review before 2026 ED138 can be called a dwarf planet rather than a candidate. For now "2026 ED138" is only a provisional designation (it encodes the year of discovery plus a survey code); a permanent name and catalogue number would be assigned later, and only if the International Astronomical Union confirms it. Second, and more exciting, this is likely just the opening. Rubin's survey is expected to catalogue thousands of new trans-Neptunian objects over its run, and to find more candidates like this one. The significance of 2026 ED138 is partly the object itself and partly what it signals: the map of our own solar system is about to get a great deal more crowded. It is the kind of patient, instrument-driven discovery we valued in our look at the Roman Space Telescope and the broader private and public space race.
Frequently asked questions
What is 2026 ED138?
2026 ED138 is a newly identified dwarf planet candidate orbiting beyond Pluto, found by the Vera C. Rubin Observatory. Early estimates put it at roughly 600 to 1,500 kilometres across, currently about 46 astronomical units from the Sun, with an orbit of around 282 years. It still needs formal confirmation.
Is there a new dwarf planet in the solar system?
There is a new dwarf planet candidate, 2026 ED138, but it has not yet been officially confirmed. If the International Astronomical Union recognises it, it would become the sixth official dwarf planet. For now it is a strong candidate awaiting follow-up measurement.
How many dwarf planets are there?
Five are officially recognised: Ceres, Pluto, Eris, Haumea and Makemake. 2026 ED138 would be the sixth if confirmed, though astronomers believe many more candidates exist in the outer solar system and expect the Rubin Observatory to find them.
Is 2026 ED138 a new planet?
Not in the major-planet sense. 2026 ED138 is a dwarf planet candidate, a world large enough to be rounded by its own gravity but not big enough to clear its orbit, so if confirmed it would join Pluto and Eris as a dwarf planet, not become a ninth planet. It is also not the hypothetical Planet Nine.
Does 2026 ED138 have a name?
Not a permanent one yet. "2026 ED138" is a provisional designation that encodes the year of discovery and a survey code. A formal name and catalogue number would be assigned later, only if and when the International Astronomical Union confirms it as a dwarf planet.
How big is 2026 ED138?
Current estimates range from about 600 to 1,500 kilometres across. The range is wide because brightness alone cannot separate a small, reflective body from a large, dark one; infrared follow-up observations are needed to narrow it down.
Is 2026 ED138 the same as Planet Nine?
No. Planet Nine is a hypothetical, unobserved large planet proposed to explain some distant orbits. 2026 ED138 is a real, observed object that is far too small to be a major planet. Finding objects like it is how astronomers hope to test the Planet Nine idea.
Has 2026 ED138 been confirmed as a dwarf planet?
Not yet. It is a candidate. Confirmation requires further observations to establish its size and orbit, and a formal classification review by the International Astronomical Union.
Saturn's south pole grew a giant 10-sided pattern: meet the decagon, the famous hexagon's stranger cousin
Hubble has confirmed a giant, evolving 10-sided jet-stream pattern, a decagon, encircling Saturn's south pole, a southern counterpart to the planet's celebrated north-pole hexagon. Here is what the Saturn decagon is, how it compares to the hexagon, and why these regular shapes form at all.
For the first time, we can see whirlpools on the Sun's surface. They may explain why its atmosphere is so strangely hot
The world's largest solar telescope has taken the sharpest images ever of the Sun's surface and caught something long predicted but never seen there: tiny plasma whirlpools about 20 km across, the wave-curl seen in ocean waves and clouds. They may help solve a decades-old mystery, but here is what it does not prove.
JWST found a 'black hole star' in the early universe, and it might solve a real puzzle
The James Webb telescope spotted an object 660 million years after the Big Bang that looks like a giant star but is really a black hole wrapped in so much gas it disguises itself. If the interpretation holds, it helps explain one of astronomy's genuine mysteries: how monster black holes appeared so impossibly early. Here is the careful version.
OpenAI's 722 AI Math Papers: Breakthrough, or Unverifiable 'Slop'?
OpenAI dumped 722 AI-generated math manuscripts on GitHub, claiming progress on famous open problems, then withdrew three a day later over a single sign error. Mathematicians are split between 'a new era' and 'we didn't ask for this.' Here is what is actually proven versus merely claimed, and why it matters.
3I/ATLAS: Comet or Alien Spaceship? What Science Says
3I/ATLAS is the third interstellar object ever found. Where it is now, what JWST and ALMA discovered, and why most scientists say it is a comet, not aliens.
Two supernova studies have reopened the dark energy debate, and they do not even agree with each other
One team says cosmic acceleration may be an illusion once you account for the ages of the exploding stars. Another says acceleration is real but dark energy is fading over time. A third camp, with two Nobel laureates, says the original measurements were fine all along. It is a fight over one cosmic ruler, not a new observation, and the referee has not blown the whistle.