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Astronomers report possible new dwarf planet candidate 2026 ED138 beyond Neptune

Scientific American reports the candidate sits about 46 times farther from the sun than Earth, with an initial diameter estimate of 600 to 1,500 kilometers.

Updated Oct 28, 2026 · 00:23 UTC1 reports

The short version

  • Astronomers at the Vera C. Rubin Observatory announced a new dwarf planet candidate, provisionally designated 2026 ED138, beyond Neptune's orbit.[Scientific American]
  • The object was identified with a search code developed by Matthew Holman and Kevin Napier, supported by sightings dating to 2016.[Scientific American]
  • Initial estimates place it about 46 times farther from the sun than Earth, tilted roughly 25 degrees, and 600 to 1,500 kilometers across.[Scientific American]
  • Formal dwarf planet status is unconfirmed; further observations are needed to determine whether it has enough mass to be round.[Scientific American]

Key facts

  • Astronomers at the Vera C. Rubin Observatory announced the discovery of a new dwarf planet candidate, designated 2026 ED138, on Tuesday.[Scientific American]
  • The discovery was made by running Rubin Observatory data through a search code developed by Matthew Holman and Kevin Napier.[Scientific American]
  • Holman and Mario Jurić found 30 more Rubin observations of the object dated between March and July 2026, plus sightings going back to 2016.[Scientific American]
  • The object is about 46 times as far from the sun as Earth and tilted about 25 degrees off the solar system's plane.[Scientific American]
  • Initial measurements indicate a diameter between 600 and 1,500 kilometers.[Scientific American]
  • Further observations are required to determine whether the object has enough mass to become round, a key requirement for a dwarf planet.[Scientific American]

What remains uncertain

  • Formal classification as a dwarf planet is unconfirmed and depends on whether the object has enough mass to become round.[Scientific American]
  • The diameter range of 600 to 1,500 kilometers is based on initial measurements and may change with further observation.[Scientific American]
  • The object does not yet have an official name and is identified only by its provisional designation.[Scientific American]

Sources

Outlet counts describe coverage, not independent confirmation. Reports may share a wire service or original source.