---
title: "Rubin Observatory identifies dwarf planet candidate 2026 ED138 at the edge of the Solar System"
description: "The Vera C. Rubin Observatory in Chile has reported a dwarf planet candidate, 2026 ED138, about 7 billion km from the Sun. Depending on its surface brightness, its diameter could range from 600 to 1,545 km."
date: 2026-10-28T12:34:59.295Z
lang: en
url: https://xab.info/en/posts/2026-ed138-dwarf-planet-candidate-rubin-observatory
tags: [dwarf-planet, vera-rubin-observatory, solar-system, pluto, iau, astronomy]
author: "Alexander Buran"
publisher: "XAB.info"
---

# Rubin Observatory identifies dwarf planet candidate 2026 ED138 at the edge of the Solar System

![Graphic representation of orbits of celestial bodies including Ceres, Pluto, and candidate 2026 ED138](https://xab.info/media/2026/10/28/2026-ed138-kandidat-v-karlikovye-planety-observatoriya-rubin/2026-ed138-kandidat-v-karlikovye-planety-observatoriya-rubin-1.webp)

## Key Points

- The Vera C. Rubin Observatory in Chile has announced a dwarf planet candidate, 2026 ED138, located nearly 7 billion km from the Sun.
- The object's diameter estimate ranges from ~600 km for a bright surface to ~1,545 km for a dark one.
- In a short time, the observatory has discovered about 2,300 objects beyond Pluto's orbit, and 2026 ED138 is the largest among them.
- Since 2006, the IAU has not added any new dwarf planets; five are recognized: Ceres, Pluto, Eris, Haumea, Makemake.

The Vera C. Rubin Observatory in Chile has unveiled its initial findings, including a celestial body temporarily designated as 2026 ED138, which scientists are considering as a dwarf planet candidate. According to data reported by Phys.org on October 28, the object is located nearly 7 billion kilometers from the Sun, far beyond the orbit of Pluto. Mario Juric, head of the observatory's Solar System research division, speaking on the sidelines of the International Astronomical Union event in Spokane, Washington, on October 27, called the discovery a potential start to a series of findings: "I hope this is just the first of many future discoveries."

### An observatory continuously scanning the night sky

The Vera C. Rubin Observatory is being implemented by the U.S. National Science Foundation in collaboration with the Department of Energy and is located on a mountaintop in Chile. Its telescope continuously scans the night sky, and in a short time, the project has detected about 2,300 celestial objects located beyond Pluto's orbit. Among all the identified bodies, 2026 ED138 stands out as the largest in size, making it the primary candidate for dwarf planet status in the observatory's current list of findings.

### Size estimates: from 600 to 1,545 kilometers

The exact diameter of the new object remains unknown as it depends on its albedo — the surface's reflectivity. Based on brightness, distance, and other factors, astronomers provide an approximate estimate: if the surface of 2026 ED138 is relatively bright and reflective, its cross-section could be around 600 km; if the surface is dark, the diameter could reach 1,545 km. Both scenarios place the object within a range that scientists consider sufficient for forming a spherical shape.

### Criteria of the International Astronomical Union

According to the IAU definition, a dwarf planet must be massive enough for its own gravity to give it a near-spherical shape. For icy objects on the outskirts of the Solar System, scientists believe this condition is most likely met by bodies with a diameter exceeding 400 km. Thus, even the lower bound of the 2026 ED138 size estimate exceeds this threshold, justifying its candidate status. Final recognition, however, will require additional observations and a formal IAU decision.

### Twenty years without new dwarf planets

The context of the discovery is significant: in 2006, the International Astronomical Union removed Pluto from the list of planets and reclassified it as a dwarf planet, recognizing a total of five such bodies — Ceres, Pluto, Eris, Haumea, and Makemake. Since then, the IAU has not added any new objects to this list, and 2026 ED138 could become the first candidate capable of expanding the list after twenty years. For now, it is a candidate, not a finalized recognition, so the object's status remains preliminary.

## Fact-Check & Sources

- [Обнаружена потенциальная карликовая планета на краю Солнечной системы.](https://www.vietnam.vn/ru/phat-hien-ung-vien-hanh-tinh-lun-o-ria-he-mat-troi) - Source: discovery of 2026 ED138 by the Rubin Observatory, distance ~7 billion km, size estimate 600–1,545 km, ~2,300 objects beyond Pluto, quote from M. Juric, five recognized dwarf planets since 2006. Status 'candidate' maintained.
- [Странная орбита и огромное "сердце": куда пропала девятая планета Солнечной системы (фото)](https://focus.ua/technologies/744297-strannaya-orbita-i-ogromnoe-serdce-kuda-propala-devyataya-planeta-solnechnoy-sistemy-foto) - Context: history of Pluto and its reclassification in 2006, consistent with the article's basis.
- [Мир на краю Солнечной системы имеет атмосферу: считалось, что это невозможно (фото)](https://focus.ua/technologies/753023-mir-na-krayu-solnechnoy-sistemy-imeet-atmosferu-schitalos-chto-eto-nevozmozhno-foto) - Контекст: история Плутона и его переклассификации в 2006 году, согласуется с основой статьи.
- [Карликовая планета или нет: загадочный объект на краю Солнечной системы](https://hi-tech.mail.ru/news/144355-karlikovaya-planeta-ili-net-zagadochnyj-obekt-na-krayu-solnechnoj-sistemy/) - Подтверждено по источнику hi-tech.mail.ru

## FAQ

### What is 2026 ED138?

It is a celestial body beyond Pluto's orbit discovered by the Vera C. Rubin Observatory, which scientists are considering as a dwarf planet candidate. It has not yet received final recognition from the IAU.

### What is the size of 2026 ED138?

The exact diameter is unknown. With a bright reflective surface, the cross-section is estimated at about 600 km; with a dark surface, the diameter could reach 1,545 km.

### Why is it considered a dwarf planet candidate?

According to the IAU definition, a dwarf planet must have a near-spherical shape. For icy objects on the edge of the Solar System, this is likely at diameters over 400 km, and both size estimates for 2026 ED138 exceed this threshold.

### Has the IAU added any new dwarf planets since 2006?

No. Since the recognition of five dwarf planets (Ceres, Pluto, Eris, Haumea, Makemake) in 2006, the list has not been updated, and 2026 ED138 could be the first candidate to join it.