# Astronomers find dwarf planet candidate 2026 ED138 with a 281.1-year orbit in Rubin data

- Published: 2026-11-14 01:50 UTC
- Section: Sky & Space › Astronomy
- Tags: 2026 ED138, dwarf planet candidate, Vera C. Rubin Observatory, trans-Neptunian object, 281.1-year orbit, Matthew Holman, Smithsonian Astrophysical Observatory, sixth dwarf planet, ALMA observations
- URL: https://realtech.media/news/rt-6a4a39e85620ae61a3bb18dd_astronomers_find_dwarf/

**Archival data from the Vera C. Rubin Observatory revealed a trans-Neptunian object estimated at 600–1,500 km across; if confirmed, it would be the sixth dwarf planet.**

![Astronomers find dwarf planet candidate 2026 ED138 with a 281.1-year orbit in Rubin data](https://realtech.media/media/2026/11/caca4a48b956fc37.jpg)
*Rubin Observatory/NSF/AURA, Wikimedia Commons, CC BY 4.0*

In October 2026, US astronomers analysing existing observational data identified 2026 ED138, a dwarf planet candidate that orbits the Sun in 281.1 years, according to gigazine.net [1]. On 13 October, Matthew Holman, a senior astrophysicist at the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, was examining data from the NSF Vera C. Rubin Observatory in Chile when he noticed an unusual object [1]. Five dwarf planets are recognised at the time of writing, so 2026 ED138 would become the sixth if it is confirmed [1].

## How the object was found

Holman and his colleague Kevin Napier had already used their own program to find more than 2,000 faint points of light in the Rubin data. Each one is a newly found small body in the distant solar system [1]. The new object turned out to be far larger than any of them [1].

Astronomers who search for distant bodies are used to false alarms. Holman said that everyone has once thought they had found Mars, and that it was a false detection; when something looks large, the team becomes very cautious [1]. He continued the checks together with Napier and Mario Jurić, who leads solar system research at the Rubin Observatory [1].

The same object also appeared in photographs taken over the past ten years, which allowed the team to narrow down its orbit [1]. 2026 ED138 is a trans-Neptunian object that may be classified as a dwarf planet, and it may be among the largest known candidates [1]. Its distance from Earth is 46 times the distance from the Sun to Earth [1].

## Size and planned observations

A dwarf planet is a small, nearly spherical body that orbits a star but has not cleared similar-sized objects from its orbit. Pluto was reclassified in 2006 because it lies amid the Kuiper belt [1]. The diameter of 2026 ED138 is estimated at about 600 to 1,500 km, large enough for it to be nearly round [1].

Brightness alone does not give the exact size. Two methods can supply the missing data: infrared observations of heat emitted by the Sun-warmed body, and observations of the candidate passing in front of a star [1]. To obtain such data, Holman is preparing an observing campaign that includes the ALMA radio telescope in Chile [1].

At the time of writing, the object sits in a position that is very hard to observe from Earth. Holman said it should become easier to observe over the coming months and that others will likely try [1]. The five recognised dwarf planets are Pluto, Eris, Makemake and Haumea in the Kuiper belt, and Ceres in the asteroid belt between Mars and Jupiter [1]. Learning where and how 2026 ED138 formed could provide new clues about the early solar system [1].

## Sources

1. [gigazine.net](https://gigazine.net/news/20261113-2026-ed138)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-6a4a39e85620ae61a3bb18dd_astronomers_find_dwarf/