Astronomers identify massive dwarf planet candidate 2026 ED138

Vera C. Rubin Observatory enables deep sky survey

The Vera C. Rubin Observatory in Chile identified the object using a large digital camera. This facility is jointly funded by the U.S.

The observatory began a 10-year sky survey in June 2026 to search for previously unseen objects. 2026 ED138 remained hidden for a long time because it sits in a crowded region near the Milky Way. Millions of stars in that area made detection difficult for earlier telescopes.

Technicians obtained the first test images from that device.

Matthew Holman identifies 2026 ED138

Astronomer Matthew Holman identified 2026 ED138 on Oct. 13, 2026.

Holman described his reaction to the discovery as "one of excited disbelief".

Defining dwarf planets in the outer solar system

Unlike a full-sized planet, it has not gravitationally cleared its orbital region of other objects.

Pluto was discovered in 1930 as the ninth planet in the solar system. It was later reclassified as a dwarf planet in 2006.

Hubble and Webb telescopes identify 27 new objects

The survey utilized Hubble to collect visible light and Webb to capture infrared light simultaneously to determine the orbits, sizes, and surface colors of the objects.

Two studies detailing the findings on the sizes, compositions, and history of these newly identified objects were published in The Astronomical Journal.

Research teams analyze TNO populations

They classified the objects into two distinct groups. Cold TNOs remain in their original formation regions with circular orbits, while hot TNOs move in elongated orbits after giant planets scattered them outward.

The study revealed that both populations share similar size distributions and surface color patterns. This suggests that planetesimal formation processes remained consistent regardless of the environment. Researchers observed fewer small TNOs than some planet formation models predicted. The surface colors of the objects suggest they experienced fewer collisions or preserved their original compositions better than scientists previously assumed.

Experts discuss planetesimal formation history

Anastasia Morgan, a PhD candidate at Northern Arizona University, said the surface composition of small objects provides clues to their history.

He said, "These dynamically 'hot' TNOs retain a signature of where they were born, even though they've been orbitally scrambled since then".

Marielle Eduardo, a PhD candidate at the University of Victoria, said the formation process creates similar sizes across different environments.