IAU Throws Pluto a Bone: "Plutoid"
Written by Nancy Atkinson
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
Filed under: Astronomy
June 12th, 2008 at 6:57 am
Plutoid sucks
June 12th, 2008 at 7:08 am
Pluto,
Please! You're not even a planet. I don't waste my time on Plutoids. Don't make me get Jupiter involved.
June 12th, 2008 at 7:12 am
A name is a name is a name…..
June 12th, 2008 at 9:16 am
I was just getting myself reconciled to "dwarf planet". (Pluto is not a 'planet'). Now this! "Plutoid"? Surely you jest!
Pluto is a Kuiper Belt Object. Ceres is a big asteroid.
K.I.S.S.
June 13th, 2008 at 5:41 am
Now it seems only logical that all the dwarf planets closer than Neptune are called Ceresoids ;-. So the current situation of dwarf planets is clear and easy to overwiev:
Plutoids: Pluto, Eris
Ceresoids: Ceres
June 13th, 2008 at 11:10 am
Pluto and Eris are simply just different classes of planets like the Large and Small Magellic Clouds. Ceres is the same, just made out of different material. If dwarf or satellite galaxies are galaxies, and dwarf stars–including the yellow dwarf we call the Sun are stars, Pluto, Eris and Ceres are planets. Remember, they were thrown into the Kuiper Belt. If Jupiter had migrated towards the Sun and knocked Earth or Mars out into the Kuiper Belt, would these be planets? The criteria does not work for extrasolar planets. We are just learning about these world in detail. Let's not rush to judgment because it does not fit our preconcieved notions. We will probably find one or two Plutoids as big as the Earth.
June 13th, 2008 at 1:33 pm
The term 'dwarf planet' was always linguistically absurd; to say that a dwarf planet (e.g. Pluto) is not a planet is exactly equivalent to saying that a brown cow is not a cow!
I think Astrofiend has got it right. 'Plutoid' solves nothing and is far too specific. Yes, I think the term 'DSSB' is not a bad idea.
Are you listening, IAU?
July 18th, 2008 at 10:13 am
So much attention is given to Pluto. What about the other planets?
When are we going to get Mercuroids (Celestial bodies in orbit around the Sun at a distance lesser than that of Venus 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.)?
What about Uranoids (Celestial bodies whose names are often made the butt of a crude joke.)?