Pluto is indeed now classified as a dwarf planet, but it's not because they found something bigger. the something bigger is Eris, btw.

the distinction between a planet and a dwarf planet is based on whether or not the celestial body has 'cleared its neighborhood' of other celesial bodies (except for stable satellites). the orbits of both Pluto and Eris take them into the Kupier belt, which is littered with thousands or possibly millions of small, icy bodies. it's sort of like the difference between a house and a condo: is there anyone else living nearby?

the only other body formally recognized as a dwarf planet is Ceres, in the asteroid belt, but there are several other candidates including 2005 FY9, Sedna, Orcus, Quaoar, and Varuna (all TNOs) as well as Pallas and Vesta (asteroids). i think it'll ultimately depend on how rough they're willing to accept when they say 'roughly spherical'. Ceres, for example, is ellipsoid and over 60kM longer than her circular diameter.

yes but by this def. jupiter has to be reclassified as a dwarf planet. at least that is what they are saying at the nine/eight planets sight.

it depends on how tightly you define 'clearing the neighborhood.' if you think it means that there's absolutely nothing nearby, then not only Jupiter, but Neptune, Mars, and the Earth wouldn't be planets.

ahem:

source: WWW Link

i personal think dwarf should be used the same gas, and rocky. ie dwarf planets, rocky planets, gas planets. thus meaning we would have two new planets not one less.

At that scale, I would call the mapsize "Silly"




What's with these weird planet definitions, everybody knows that a celestial object is a planet if it's invadable.

What are you all talking about? Pluto's a dog.

Regardless, if space combat at actual scale would be unplayable and boring, do you think space combat at an actual scale in real life would be boring, and quite hard? I mean, so many people wrote books with space combat in them, but I'm guessing space combat would only occur around actual planets, because the probability of actually meeting someone in all that space is next to nill without huge ships.

star trek writer don't know which one said combat was months of boredom and seconds of heck(changed the word.)

good luck invading Jupiter, and a space station, which can be invaded, is a celestial object: does that make it a planet? good joke though.



did you miss something? they ARE called "dwarf planets."

however, i'm not actually sure if the IAU employs a formal distinction between terrestrial planets and gas giants. it probably hasn't come up because there's such an obvious distinction between the two in our own solar system. according to the current IAU definition, planets must revolve around the sun (i.e., our sun). it was their way of delaying further discussion about the definition of planets and various possible subplanet-types that orbit other stars. there may be types of planet we've never imagined, and i think the IAU doesn't want to start creating defintions before they have at least some evidence to use based on other star systems. it may well turn out that our solar system is a freakish anomaly.

in any regard, what's in a label? "a methane atmosphere by any other name..."

well before they came out with their classification for dwarf planets. i was thinking the of the descriptive ice dwarf.

it sounds like you want their classifications to match up with the planet types from Space Empires IV...  

no i was just going with what they are supposed to be made of mostly ice.

i see. well, Ceres isn't mostly ice; it's ice and rock in about equal proportions, at least as far as we can tell.

it's relatively easy to tell what a celestial body is made of if we can see it at all, but they're small and pretty distant; even Hubble only gets fuzzy visuals.

i believe the idea behind the current definition was to facilitate easy, clear-cut distinctions. it's a lot easier to detect if a body orbits our sun, if it's spherical, and if it's gravity is the center of town, so to speak.

i think the current definition comes down to the prestige one gets from discovering and therefore naming a planet or celestial object. the IAU also maintains international rules about how things should be named. Trans-Neptunian objects are supposed to be named in relation to creation myths, but the rules for planets are different.

though you might find it interesting that some astronomers refer to Uranus and Neptune as "ice giants" because their makeup and size is different enough from Saturn and Jupiter. keep in mind this is only the IAU's definition. some astronomers still call Pluto a planet, and some never considered it a planet. each individual is free to think of things as s/he sees fit; the IAU only comes up with definitions and common naming systems so that we can understand each other.

you mean like, porn mode?

mumblefratz just got an erection

then call it a dwarf rock