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Rubin observations reveal 2026 ED138, a large dwarf-planet candidate

Observations from the Vera C. Rubin Observatory have revealed 2026 ED138, a large object considered a dwarf-planet candidate. Its identification adds a promising candidate to the search for and study of dwarf planets in the Solar System.

AI-assisted synthesis · Based on 5 outlets' reporting · Article text read from 4 of 5 outletsHow it's made

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5 outlets2 regionsLatest reporting 3 min read
Coverage: Too few ratedL 0 · C 1 · R 1 · 3 unrated

What happened

Key facts

  • The object carries the provisional designation 2026 ED138 and is a dwarf-planet candidate discovered in Rubin Observatory observations (per New York Post, ssbcrack.com, ua.news).
  • The International Astronomical Union’s Minor Planet Center announced the object under its provisional designation (per martincid.com, New York Post, ssbcrack.com).
  • Jurić described the object as roughly 1,000 kilometers across and said finding an object that large may happen about once in a generation (per martincid.com).

The brief

Researchers have identified 2026 ED138 in observations from the Vera C. Rubin Observatory, adding a large candidate world to the known population of objects beyond Neptune. The International Astronomical Union’s Minor Planet Center announced it under the provisional designation 2026 ED138.

Its discovery emerged while Rubin was still being commissioned, before the observatory began its planned Legacy Survey of Space and Time. Astrophysicist Matthew Holman spotted the object while analyzing Rubin observations with software developed alongside colleague Kevin Napier.

The New York Post reports that the team traced it through 30 detections over 20 nights, spanning 4 March to 11 July 2026. Researchers also located it in older Dark Energy Camera images dating to February 2016, extending the observational record beyond Rubin’s newer data. The available size estimates are substantial but imprecise.

Jurić described ED138 as roughly 1,000 kilometers across and told GeekWire that finding an object of that scale may occur about once in a generation. Another account gives a wider estimated diameter range of 600 to 1,500 kilometers, explaining that uncertainty about surface reflectivity complicates the calculation. The New York Post says its size may rival Makemake and Haumea.

Those estimates do not settle whether ED138 qualifies as a dwarf planet. Universe Today describes it as an unconfirmed candidate and quotes Holman saying that confirmation would add it to a small group of worlds. The candidate label therefore reflects a possible classification, not a confirmed status.

Its provisional designation and detection are distinct from that unresolved classification. The object’s orbit offers another measure of its scale and distance. The Minor Planet Center’s figures put its orbital period at about 281 years, with its distance from the Sun ranging from 36.86 to 49.04 astronomical units.

A separate account compares Pluto’s average distance at 40 astronomical units; another gives Pluto’s orbital range as 29.6 to 49.08 astronomical units. These comparisons place ED138’s path in the outer Solar System, while showing that its closest and farthest points span a broad range.

Jurić characterized ED138 as the largest trans-Neptunian object found in about 20 years and said Rubin found it during telescope commissioning. That claim underscores the scientific significance researchers attach to the discovery, while the size range and outstanding dwarf-planet classification remain uncertain.

Rubin is expected to find more objects of this kind, and its planned survey will provide a larger body of observations for studying the distant Solar System.

Why it matters

  • Researchers estimate ED138 may be roughly 1,000 kilometers across, with a broader 600-to-1,500-kilometer range; uncertainty about reflectivity affects how confidently its size can be assessed.
  • The candidate’s classification matters because confirmation would add a large object to the small family of dwarf planets described by Holman.
  • The observations extend from Rubin detections in 2026 to older Dark Energy Camera images from February 2016, giving researchers a longer record for studying ED138’s orbit.
  • Its estimated 281-year orbit and 36.86-to-49.04 astronomical-unit distance range make ED138 a useful object for studying the outer Solar System.

What to watch next

  • Whether researchers confirm ED138 as a dwarf planet, a classification Universe Today says remains unconfirmed.
  • Whether further study narrows the estimated diameter range of 600 to 1,500 kilometers by resolving uncertainty about surface reflectivity.
  • Whether Rubin’s planned Legacy Survey of Space and Time identifies additional large objects like ED138.
  • Whether analysis of the Dark Energy Camera images dating to February 2016 adds to the object’s observational record.

How it's being covered

Coverage analysisShow details
5 source articles · 5 unique outlets
Outlet political mix: Too few rated· 1 Center · 1 Right · 3 unrated
Where the outlets are based: Unknown 40% · US/Canada 20% · Other 40%
Outlet political mix
Too few rated
Left
Center
Right
0 outlets
1 outlet
1 outlet
The marker shows coverage balance: each unique outlet counts once. 3 unrated outlets are not included.
Geography
Where the outlets covering this story are based.
5 unique outletsDominant coverage: US/Canada
How we measure coverage

How outlets' accounts compare

1 factual disagreement · 2 framing differences · 2 uncorroborated claims · 3 information gaps
Sources disagree on one factual point.Compared across 4 reports whose article text Updat3 read; 1 other outlet was checked by headline only.
Factual disagreements
Sources report different numbers, dates, attribution or causes for the same thing.
  • ED138’s estimated size remains uncertain: one account gives a 600-to-1,500-kilometer range, while Jurić describes it as roughly 1,000 kilometers across; the reported uncertainty concerns the estimate, not necessarily a conflict in measurements.
Updat3: The evidence conflicts; Updat3 does not present either version as established.
Framing / emphasis differences
Sources emphasise different angles, actors or consequences of the same reporting.
  • The New York Post emphasizes Holman’s identification and the older Dark Energy Camera observations; martincid.com foregrounds Jurić’s estimate of roughly 1,000 kilometers and the rarity of finding an object that large.
  • news.ssbcrack.com gives a broad estimated diameter range of 600 to 1,500 kilometers and highlights uncertainty from surface reflectivity; the New York Post instead says the object may rival Makemake and Haumea.
Updat3: These are differences of emphasis, not disputes about what is reported. They do not show that the reported claims are true.
One-sided or uncorroborated claims
Claims that come from one party or one source family and are not independently corroborated.
  • Jurić told GeekWire that finding an object roughly 1,000 kilometers across may happen about once in a generation.
  • Holman said that confirming ED138 as a dwarf planet would place it among a small family of worlds.
Updat3: Not independently corroborated yet — treat as a claim, not an established fact.
Not established by the reporting
Information the available reporting does not contain or confirm. This is a gap, not a disagreement.
  • Universe Today stresses that dwarf-planet status is unconfirmed and places the finding before Rubin’s planned primary survey.
  • The accounts do not give a direct measurement of ED138’s diameter or its surface reflectivity.
  • Whether ED138 qualifies as a dwarf planet remains unresolved.
Updat3: Updat3 cannot conclude anything about this from the current sources.

Timeline

Developments from this story's sources, dated background we compiled and fact-checked, and our earlier coverage. Each row says which.
  1. Clyde Tombaugh discovered Pluto at Lowell Observatory.
    Background · compiled and fact-checked by Updat3
  2. The search for objects beyond Neptune gained a major observational foothold on August 30, 1992, when astronomers David Jewitt and Jane Luu reported 1992 QB1, the first confirmed Kuiper Belt object after Pluto and Charon.
    Background · from our historical context
  3. The International Astronomical Union defined the dwarf-planet category and reclassified Pluto as a dwarf planet.
    Background · compiled and fact-checked by Updat3
  4. The Vera C. Rubin Observatory released its first images.
    Background · compiled and fact-checked by Updat3

How we got here

Before the 2026 announcement, the Vera C. Rubin Observatory had begun producing images that could be searched alongside older survey data: it released its first images on June 23, 2025, after years of construction and commissioning in Chile.

The archival observations relevant to searches for distant objects included images from the Dark Energy Camera (DECam), which saw first light on the Victor M. Blanco Telescope in September 2012; the Dark Energy Survey used it from 2013 to 2019.

Original sources

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