IAU Throws Pluto a Bone: "Plutoid"

By Nancy Atkinson - June 11, 2008 at 11:16 AM UTC | Planetary Science
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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 Atkinson

Nancy Atkinson is a space journalist and author with a passion for telling the stories of people involved in space exploration and astronomy. She is currently retired from daily writing, but worked at Universe Today for 20 years as a writer and editor. She also contributed articles to The Planetary Society, Ad Astra (National Space Society), New Scientist and many other online outlets.

Her 2019 book, "Eight Years to the Moon: The History of the Apollo Missions,” shares the untold stories of engineers and scientists who worked behind the scenes to make the Apollo program so successful, despite the daunting odds against it. Her first book “Incredible Stories From Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos” (2016) tells the stories of 37 scientists and engineers that work on several current NASA robotic missions to explore the solar system and beyond.

Nancy is also a NASA/JPL Solar System Ambassador, and through this program, she has the opportunity to share her passion of space and astronomy with children and adults through presentations and programs. Nancy's personal website is nancyatkinson.com