Scientists have identified a distant object beyond Neptune that could become the sixth officially recognised dwarf planet in the Solar System. Named 2026 ED138, the object is estimated to be between 600 and 1,500 kilometres across, placing it among the largest potential dwarf planets found in the outer Solar System.

The discovery was announced on October 27 by the International Astronomical Union’s Minor Planet Center. Researchers identified the object using observations from the Vera C. Rubin Observatory in Chile, offering fresh insight into the distant regions beyond Pluto.

How was 2026 ED138 discovered?

Astrophysicist Matthew Holman of the Harvard-Smithsonian Center for Astrophysics identified the object on October 13 while examining astronomical data collected earlier in 2026. He used software developed with his colleague Kevin Napier to track moving objects among billions of astronomical detections.

Reflecting on the discovery, Holman said, “My first reaction was one of excited disbelief.”

He added, “Objects like this are very rare, so I immediately started checking whether I or the code had done something wrong.”

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Subsequent analysis showed that the Rubin Observatory had captured the object 30 times across 20 nights between March 4 and July 11, 2026. Researchers also found it in archival images taken by the Dark Energy Camera in February 2016, indicating that the object had remained unidentified for years.

Scientists discover 1,500 km-wide object beyond Pluto
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(Representational Image) A mysterious object beyond Neptune could become the Solar System’s sixth recognised dwarf planet | AI Generated

What do scientists know about the distant object?

2026 ED138 is located approximately 46 astronomical units from the Sun. One astronomical unit represents the average distance between Earth and the Sun.

A research paper published on arXiv estimates that its orbit is inclined by approximately 24.4 degrees relative to the plane of the Solar System.

Its position against the crowded background of the Milky Way may explain why previous observations failed to identify it. Scientists have yet to establish its precise diameter because its surface reflectivity remains unknown.

However, its estimated size raises the possibility that gravity has shaped it into a roughly spherical body, one of the requirements for dwarf planet classification.

Could 2026 ED138 become the sixth recognised dwarf planet?

Further infrared observations are needed to determine its actual size and establish whether it meets the criteria for official recognition.

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If confirmed, 2026 ED138 would join Pluto, Ceres, Eris, Haumea and Makemake as the sixth officially recognised dwarf planet.

The Vera C. Rubin Observatory’s planned decade-long sky survey could also reveal more distant objects that earlier surveys missed.

Holman said, “Rubin will image the whole southern sky again and again for ten years,” adding, “so any others hiding in the places earlier surveys skipped are now within reach.”