Categories: Astronomy

IAU Throws Pluto a Bone: “Plutoid”

Almost two years after the International Astronomical Union (IAU) General Assembly demoted Pluto from a “real” planet to the new category of dwarf planets, the IAU, as promised, has decided on a name for trans-Neptunian dwarf planets similar to Pluto. The name “Plutoid” was proposed and accepted by the IAU at its recent meeting in Oslo, Norway. Here’s the definition of a Plutoid: “Celestial bodies in orbit around the Sun at a distance greater than that of Neptune that have sufficient mass for their self-gravity to overcome rigid body forces so that they assume a hydrostatic equilibrium (near-spherical) shape, and that have not cleared the neighborhood around their orbit.” The two known and named Plutoids are Pluto and Eris. It is expected that more Plutoids will be named as science progresses and new discoveries are made, for example, when the New Horizons mission arrives at the Kuiper Belt region in 2015.

Ceres, however, although a dwarf planet, is not a Plutoid, as it is located in the asteroid belt between Mars and Jupiter. Astronomers believe that Ceres is the only object of its kind. Therefore, a separate category of Ceres-like dwarf planets may be defined and named at a later date.

The IAU has been responsible for naming planetary bodies and their satellites since the early 1900s, and oversees the assignment of names to surface features on bodies in the Solar System.

The IAU confirmed that in French plutoid is “plutoïde,” and in Spanish “plutoide.”

Sources: PhysOrg, International Astronomical Union

Nancy Atkinson

Nancy has been with Universe Today since 2004, and has published over 6,000 articles on space exploration, astronomy, science and technology. She is the author of two books: "Eight Years to the Moon: the History of the Apollo Missions," (2019) which shares the stories of 60 engineers and scientists who worked behind the scenes to make landing on the Moon possible; and "Incredible Stories from Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos" (2016) tells the stories of those who work on NASA's robotic missions to explore the Solar System and beyond. Follow Nancy on Twitter at https://twitter.com/Nancy_A and and Instagram at and https://www.instagram.com/nancyatkinson_ut/

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