Celestia Forums

FYI

The International Astronomical Union has decided on the term "plutoid" as a name for Pluto and other objects that just two years ago were redefined as "dwarf planets."

Nasty

Hmmm...

I like it.

BobHegwood wrote:Hmmm...

I like it.

I don't like it. According to the new definition, only Pluto and Eris are now "plutoids". Ceres is either still a dwarf planet or an asteroid again. I'm afraid it's not clear yet.

Paul

Oh great, yet another locally-restricted term that unnecessarily confuses things. The term applies to all large objects orbiting the Sun beyond the orbit of Neptune, which makes it meaningless for planetary systems in general, and in any case the class does not seem particularly distinctive enough from the point of view of understanding the population of objects that are out there either. At least it isn't the geologically-ignorant "pluton" that was proposed before.

(Furthermore, has the matter of whether dwarf planets are actually regarded as members of the population of smaller objects among whose orbits they are found? Is Ceres the largest asteroid, or does its dwarf planet status negate its membership of the asteroid category? - from what I've seen, it seems to be that the latter is true, which makes no sense whatsoever from a population-based viewpoint)

SU(3)xSU(2)xU(1) wrote:

BobHegwood wrote:Hmmm...

I like it.

I don't like it. According to the new definition, only Pluto and Eris are now "plutoids". Ceres is either still a dwarf planet or an asteroid again. I'm afraid it's not clear yet.

Paul

Oh, okay... I didn't understand that asteroids were also considered "plutoids." I had just assumed that they were to be used for large "planet-sized" objects outside of the known Solar System. Hell, what do I know?

Actually yes, this is truly excellent: according to the IAU official quoted at the end of this news report, Ceres is NOT an asteroid. This basically means that given a population of objects, the largest members of that population are not in fact members of the population.

This terminology seems to me stupid and divorced from reality.

Yay--so now we can say 'plutoid' instead of 'bright KBO'?

To me, plutoid seems like a useless addition to planetary nomenclature. I don't think that there's any need to support it in Celestia: planet, dwarf planet, and asteroid are already adequate. Whatever criticisms one might have of the term 'dwarf planet', at least it can plausibly be used as a category for bodies outside our own Solar System. Both the brightness and semimajor axis criteria for plutoid make it impossible to apply to exoplanets. Mike Brown muses about some interesting consequences of the brightness criterion here: http://www.mikebrownsplanets.com/2008/0 ... fever.html
(Quick summary: cover Pluto with dirt and it's no longer a plutoid.)

--Chris

Its sad to think that the bulk if not all of this stems from Pluto was demoted from [full] planetary status. I don't necessarily agree with the IAU definition because it rules out some more of the strange phenomenon like a binary planet pair [two planets orbiting a common center of gravity which orbits a star) or a rouge planet, [a planet that was ejected from another system and is cursing through a nearby system] or even a planet with a highly elliptical orbit. Still stick with the general definition.

Its of course not confirmed but they are starting to think that certain perturbations in the ort cloud could be do to a planet with a mass of 0.30 to 0.70 of Earth's mass. This means a planet possibly the size of Mars to 3/4 the size of Earth. If in fact they find this ort cloud giant are they going to call it a blasted plutoid as well. Give my a break. This is the most ridiculous term they have come up with yet. They just need to leave things alone.

Pluto is a dwarf planet, period. So is Ceres and the rest of the larger ort cloud objects. If they need to use this plutoid term than reserve it for smaller Enceladus size objects and leave well enough alone.

The makers of educational books, I read in one article are totaly lost as what is what. So while they keep changing everythings name and designation all education editing and printeing is suppose to come to a stand still. Please!

They have already made a choice. Just because some don't like the new designation is too bad. I feel the term dwarf planet is perfect.

Leave the dam Plutoids to Disney.

That's my 2 cents.

Don. Edwards

Don. Edwards wrote:Its of course not confirmed but they are starting to think that certain perturbations in the ort cloud could be do to a planet with a mass of 0.30 to 0.70 of Earth's mass. This means a planet possibly the size of Mars to 3/4 the size of Earth. If in fact they find this ort cloud giant are they going to call it a blasted plutoid as well. Give my a break. This is the most ridiculous term they have come up with yet. They just need to leave things alone.

Pluto is a dwarf planet, period. So is Ceres and the rest of the larger ort cloud objects. If they need to use this plutoid term than reserve it for smaller Enceladus size objects and leave well enough alone.

The makers of educational books, I read in one article are totaly lost as what is what. So while they keep changing everythings name and designation all education editing and printeing is suppose to come to a stand still. Please!

They have already made a choice. Just because some don't like the new designation is too bad. I feel the term dwarf planet is perfect.

Leave the dam Plutoids to Disney.

That's my 2 cents.

Don. Edwards

That for me was the entire problem with the IAU decision making was the lack of a "What if" scenarios. If such a [sic] planet is found then I think they are going to have one hell of a time trying to clasify it as a dwarf planet when its larger then Mercury. At this point the IAU should just adopt http://www.onewest.net/~dollan/ARCpclindex.html as the official standard. At lease its more consistent.