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IAU Classifies Pluto & Eris As "Plutoids"
Kligat writes "The International Astronomical Union has decided that Pluto and Eris should be classified as "plutoids," alongside their 2006 classification as dwarf planets. Under the definition, the self-gravity of a plutoid is enough for it to achieve a near-spherical shape, but not enough for it to clear its orbit of its rocky neighbors, and the plutoid orbits the Sun beyond Neptune."
Reader FiReaNGeL links to a
similar story at e! Science News.
How they are classified means what to whom? Someone needs their grant pulled for gross misuse of time.
*sigh*
The new definition of "planet" was quite good. Clear, straight to the point, and easy to apply to any object. Now, they add a new category that applies only to our solar system?
Okay, we won't be seeing objects this small on other star systems, but the point remains. We are already at a time when we know these objects should exist in many other places in the universe. The classification shouldn't depend on their position inside our solar system, it should be generic enough that we won't have to change it (again) when we see one of those around Alpha Centaurii. I thought this was the single most important thing to come out of the previous discussion about what should be considered a "planet".
Yeah, leave all that pesky "classification" and "definition" nonsense to hard sciences like Astrology and leave our fuzzy-wuzzy Astronomy alone!
P.S. Hail Eris!
They didn't do any more research. Nothing scientific was done. No more information was found out or cataloged. Nothing interesting happened. Just a bunch of people with too much time on their hands gave yet another name to a celestial body that orbits the sun. Frankly, who cares?
No, definitions of planets are important if you're looking for them elsewhere and wish to classify the objects you find orbiting other stars. Besides, even as a first year astronomy student five years ago I knew Pluto wasn't a planet, they only made it official recently (and properly defined planets).
This plutoid business is silly though and only serves as some sort of consolation prize to the people who still wish that planets weren't actually defined and Pluto could still be considered among them. I mean, unless we're actually going to be applying this standard to objects we find around other stars (which I think would be silly, but then I'm not a planetary astronomer... so who knows).
I suspect that this has something to do with the upcoming international year of astronomy, which is all about getting the public excited about astronomy, semi-reversing Pluto's demotion (which appears to have been unpopular among non-astronomers) seems to be good for this.
what's that now?
Yeah, I just question the decision to include 'clear the orbit' in the definition for a planet, which is what started this whole mess. If they had just stuck with the simplest definition of hydrostatic equilibrium (round shape) they could upgrade Ceres, keep Pluto, and deal with Eris. I think it would be a lot more exciting to have new planets than this constant squabbling over the status of Pluto
Pluto officially defined as Pluto.
Eris officially seen as similar to Pluto.
Who really gives a flip?
There are objects out there of every size shape and configuration possible.
See my blog at Who's Who
By saying this you (and people agreeing with you - yes, you know who you are!) show you didn't put any effort into understanding what "clearing neighbourhood" in planet definition means.
/. summary is to be trusted, is specific to our system.
Specifically, it doesn't say that no other bodies in vicinity are present, but that all of them are dominated by gravitational influence of a planet. And that's definatelly the case with Moon and near Earth asteroids. But not with Pluto - it's in orbital resoncance with Neptune.
I actually really like this definition, fairly precise, universal, and avoids waking up one day in a Solar System with 20 or 30 planets, once we start discovering more Pluto-like objects. But somehow we have this nonsence of people attaching sentimental value to the notion of Pluto beeing a planet, which makes the whole deal unpopular.
And BTW, I don't like this latest "plutoids" thing; looks more like PR stunt. Definatelly doesn't really resolve anything, and if
One that hath name thou can not otter
Should we also have made an exception for Ceres for historical reasons? It was thought to be a planet for some 50 years after its discovery until whole bunches of asteroids were discovered.
There's no hard limit as a number, but there has to be some limit, otherwise every dust particle that orbits the sun should be classified as a planet.
I think the current definition is pretty good. Although I feel some sympathy for Pluto, I feel it's not quite right to classify a small body whose orbit intersects the orbit of a gas giant as a planet.
The irony of it all is that Pluto would never have been considered a planet if it wasn't for some error in observations that led people to believe its perturbation of Neptune's orbit to be much greater than it really is.
You have to draw the line somewhere, especially if there's a chance that we'll end up with a lot more than 30 (it shows the signifance of given object for the Solar System as a whole vs. the significance of a lot of objects as quite homogonous group). For example, Ceres was ALSO initially considered a planet...right until the point when we started to discover the rest of asteroid belt.
;P ) hint that Pluto is simply a similar "first", discovered by chance because it was back then close to eclyptic and close to predicted position of Planet X (Uranus/Neptune - like object predicted by perturbations in Neptune orbit - later measurements shown them to be non-existent)
All signs on heaven (and...only on heaven
One that hath name thou can not otter