Astronomers have identified a dwarf planet candidate designated ED138 located beyond Pluto. The object measures between 600 kilometres and 1500 kilometres across.
Objects with a diameter exceeding approximately 600 kilometres are generally large enough to be classified as dwarf planets. The International Astronomical Union currently recognises five official dwarf planets: Ceres, Pluto, Haumea, Makemake and Eris.
Sedna and Quaoar are also considered unofficial members of the dwarf planet group. Matthew Holman first spotted ED138 in October.
Mario Jurić found 30 additional observations of the object since March. Archival records of ED138 date back as far as 2017.
Holman and Jurić presented their findings at the Annual Division for Planetary Sciences meeting in Washington on 27 October. ED138 requires about 281 years to complete one orbit around the sun.
The orbit of ED138 is tilted roughly 25 degrees relative to the plane of the solar system. Mario Jurić at the University in Washington said, "Rubin is giving us an unprecedented capacity to explore the sky through a combination of speed, depth, and precision."
Jurić added that identifying a new object allows researchers to search back months or even decades to find it in images where it was previously overlooked. Holman stated, "Rubin will image the whole southern sky again and again for ten years, so any others hiding in the places earlier surveys skipped are now within reach."
