Chile’s Vera C. Rubin Observatory has identified its first dwarf planet candidate, 2026 ED138, according to an October 27 announcement from Rubin and SLAC National Accelerator Laboratory. The distant object remains unconfirmed as a dwarf planet, with an estimated diameter of 600–1,500 kilometres.
The team puts its current distance at about 46 astronomical units, compared with Pluto’s average of about 40. One unit represents the average Earth–Sun distance. Its brightness, distance and assumed surface reflectivity underpin the size estimate; infrared measurements must narrow that uncertainty.
Matthew Holman of the Center for Astrophysics | Harvard & Smithsonian found the object on October 13 using software developed with Kevin Napier. The program links detections of moving objects across images. Rubin recorded it 30 times over 20 nights between March 4 and July 11, the observatory said.
Archival Dark Energy Camera images extended the record back to 2016, allowing the researchers to trace more than a decade of its orbit. The object appeared against a dense field of Milky Way stars, helping explain why earlier searches missed it. Repeated imaging and software separated its movement from that crowded background.
Rubin said the orbit’s tilt of almost 25 degrees suggests past gravitational disturbance by Neptune. Such bodies help scientists reconstruct planetary migration and the Solar System’s formation. Follow-up observations will test whether this icy object is large enough for gravity to make it round, a necessary condition for dwarf planet status.
Comments