Definition of Planet to be Announced in September 200
MasaMuneCyrus writes "After over seven years of debating, the International Astronomical Union announced that it expects to announce the official definition of a planet in September. After many-a-deadlock, they handed the task of deciding exactly what a planet is to a new committee, which includes historians and educators. 'They wanted a different perspective from that of planetary scientists,' said Edward Bowell, an astronomer at Lowell Observatory who is also vice president of the IAU's Division III-Planetary Systems Sciences group. If all goes according to plan, the wording will be proposed in their 12-day General Assembly meeting in Prague."
That's no moon! (Score:3, Funny)
Re:That's no moon! (Score:2)
This is all too much, I hate the future.
anyone want to place bets on (Score:4, Informative)
I've been 50-50 on it myself. I'm a fan of anything Arizona (having lived there), but apart from the moon system, I'm hard pressed to call it a planet.
If Pluto sticks - then there's probably 100s of Kuiper Belt objects that qualify.
Re:anyone want to place bets on (Score:2, Informative)
terrestrial, jovian, cometary (Score:4, Interesting)
As Jesapoo points out, it's not about size, but as important as orbit eccentricity is material composition. Planets are historically categorized into two buckets based on their composition -- "terrestrial", which are mostly rock (mercury, venus, earth, mars), and "jovian", which are mostly gas (jupiter, saturn, uranus, and neptune). And then there are comets, which are mostly dirty ice and frozen gas with some rocks.
Pluto is cometary in composition, which has led some to classify it as a comet rather than as a planet. Frankly I can see the argument. Perhaps the best way out is to define "planet" such that some comets can be planets?
-- TTK
Re:terrestrial, jovian, cometary (Score:2)
Re:terrestrial, jovian, cometary (Score:3, Insightful)
Earth like, 4 samples
Jupiter like, 4 samples
Pluto like, 2 samples (including Xena)
Why the push to go from three types back down to two? Sheesh, the gas giants are so much larger than the rocky planets maybe only those should be called planets. Reclassifying Pluto as a large "Kuiper belt object" makes little more sense that making Earth a large "Close orbiting asteroid".
Re:terrestrial, jovian, cometary (Score:2)
1: there are a lot of objects that are pluto like, all but one so far are smaller than pluto but i don't belive there is a huge margin. Scientists HATE drawing arbitary lines in a known continum.
2: its just pluto and xena now but with more KBOs being discovered all the time is it going to stay that way.
"Moon system" (Score:5, Interesting)
OTOH the other two moons are small enough to be called moons.
Pluto wins hands-down because... (Score:3, Insightful)
Therefore whatever definition is used, Pluto will always be included as a planet.
Same reason why American's will always keep the penny. Ego and historical pride.
Re:Pluto wins hands-down because... (Score:2)
Huh? Our currency is one of the only decimal systems we use, why would someone want to replace it?
Re: (Score:3, Interesting)
Re:anyone want to place bets on (Score:2, Interesting)
Re:anyone want to place bets on (Score:3, Funny)
a, e, i, o, u, and sometimes y
Planets:
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and SOMETIMES Pluto
Why waste any more time (or money) on this? Add "sometimes Ceres" et al. if you want. Doesn't matter
what you call it, its still a hunk of rock in space (except for the ones that aren't hunks of rock, but I digress).
Rock, Paper, Scissors (Score:5, Funny)
Maybe they should break the deadlock over Pluto by playing one (1) game of Rock, Paper Scissors.
Re:anyone want to place bets on (Score:2)
Need a new mnemonic, people!
(side note, why is mnemonic such a hard word to spell... and for that matter, why is abbreviation such a long word?)
New mnemonic (Score:2, Funny)
In October... (Score:5, Funny)
Re:In October... (Score:3, Insightful)
Your comment is starting to make perfect sense.
Re:In October... (Score:4, Funny)
Will they finally discount pluto? (Score:5, Interesting)
Then there's the fact that it only really got counted as a planet in the first place because astronomers at the time of it's discovery were hung up on the idea of discovering a ninth planet. They thought they found a disturbance in Neptune's orbit, which they attributed to a ninth planet, but ended up being caused by the fact that they were working from bad data about Neptune's mass. Pluto's much too small to have any effect on Neptune's orbit.
This might finally put the final nail in the coffin of the idea of nine major planets in our solar system. We can only hope.
I'm even more of a hardass than you (Score:2)
Re:I'm even more of a hardass than you (Score:2)
* Not related to television shows about annoying holograms and highly evolved cats
Re:Will they finally discount pluto? (Score:3, Funny)
Well, sir, I hope that you are similarly excluded from the human definition. What have I ever done to you to deserve this?
-Pluto
(PS that was a really low blow, commenting on my size. I could make a crack about you and satisfying your wife, but that wouldn't be "big" of me.)
Re:Will they finally discount pluto? (Score:3, Funny)
Re:Will they finally discount pluto? (Score:3, Interesting)
E.g., maybe other planetary systems have more planets out of the elliptical plane, if they even have one, and might have even more irregular orbits than that of Pluto.
Re:Will they finally discount pluto? (Score:2)
Re:Will they finally discount pluto? (Score:2)
Granted, I don't really know what I'm talking about, but it seems at least possible.
Re:Will they finally discount pluto? (Score:2)
No, but that's the theory for how our solar system formed, and there's plenty of visual evidence now that circumstellar disks are quite common. However, if another star wanders too close, it is possible for such planets to be bumped out of orbit. Also, just recently astronomers discovered some systems with central bodies not too much larger than jupiter [slashdot.org], so it seems planet-sized objects can form all on their own too.
Re:Will they finally discount pluto? (Score:2)
It's the plane of the ecliptic, not elliptic (it's okay, the OP made the same mistake). This was named such by the ancient astronomers as it was the narrow band in the sky where eclipses of the Earth's moon were observed to happen. They observed that it turned out that all of the wandering stars (i.e., planets) traveled within this band as well. It's not strictly speaking a plane, but a range of planes at relatively small angles t
Re:Will they finally discount pluto? (Score:2)
After all, a telluric planet as Mercury shares very few similarities with a gaseous planet such as Jupiter, and we are still calling both of them planets.
Re:Will they finally discount pluto? (Score:2)
Basically, I'd call Pluto as "grandfathered" in forget about it. I'm not even convinced that it really matters, some scientists and pedants harrumphing doesn't change the solar system, just what they call certain bodies.
Sailor scouts (Score:2)
Will she become Sailor Kuiper? Would she be the first of the Outer Outer Senshi, to be joined by Sailor Oort at a later date?
Re:Will they finally discount pluto? (Score:2)
Re:Will they finally discount pluto? (Score:2)
The Earthling Who Went To an Asteroid But Came Back From a Planet
Plot Summary:
Two Earth astronomers visit the small Kuiper Belt Object of Pluto, to measure what is claimed to be the "last planet inside of the Solar System". It's 2117, and the Jupiter-Saturn war continues. The settlers are very proud of their "planet", and are understandably dissapointed and furious to find that it is in fact an "asteroid". Not to be outwitted by a rule (and the Earthlings who enforce it), the villagers set out to make the
How about the following? (Score:3, Interesting)
Major planets: the eight (Mecury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune).
Minor planets: the moon, all the spherical satellites of the major planets, Pluto, all the spherical asteroids in the asteroid belt and all similar spherical kuiper belt objects.
Re:How about the following? (Score:3, Interesting)
Plus, how do brown dwarf stars fit into that definition? A brown dwarf can't fuse hydrogen, and in many regards is similar to a planet; however it can fuse deuterium, so it does undergo fusion during it's initial collapse. Wouldn't a brown dwarf fit your definition of a major planet, sinc
he has it right (Score:2)
A brown drawf fusing deuterium is damn well undergoing fusion. It's a star. I think we also need to exclude anything that majorly violates newtonian physics, like a neutron star or black hole.
Last week we got a name for "rogue planet". It was something like "planemo", starting with "plan" and ending
Re:How about the following? (Score:2)
Re:How about the following? (Score:2)
Re:How about the following? (Score:2)
Re:How about the following? (Score:2)
Mountains are the concern.
Earth's mountains are not significant. The highest mountain is about 1/1000 of the Earth's radius.
Re:How about the following? (Score:2)
Real Planets: the eight (Mecury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune).
Bullshit Planets: the moon, all the spherical satellites of the major planets, Pluto, all the spherical asteroids in the asteroid belt and all similar spherical kuiper belt objects.
Now who in their right mind - or what self-respecting scientist - is going to split hairs over a "Bullshit
Re:How about the following? (Score:2)
The problem is that it is equally correct to say that the Earth orbits the Moon, as it is to say the Moon orbits the Earth. Its just a question of degree and perspective.
Re:How about the following? (Score:2)
At least that's how I learned it.
Mycroft
Re:How about the following? (Score:2)
Which is fair enough but I am reminded of two moons of (I think) Saturn which share an orbit. At any one time one of them is in a slightly lower orbit than the other. When they meet they do a half circle around each other and exchange orbits.
More than any other pair of objects orbiting the sun, earth and moon appear to be in a similar relationship to this pair of moo
Re:How about the following? (Score:2)
Mycroft
There's a bigger problem that needs addressing (Score:2)
Any objective observer looking at the solar system from a stellar perspective [see note below] would describe the Earth and Moon as a double planet system. Each of these planets has significant dynamic features that cannot be accounted for without acknowleding the tidal effects of the other.
The taxonomy of astronomy is not going to make any sense until astronomers openly accept this, despite their personal, historical and cultural biases. It is now time for scientists to accept the Moon as a planet in it
Re:actually I meant... (Score:3, Informative)
Re:actually I meant... (Score:2)
Thus any D20 in comets that impact the sun probably fuses.
Any definition is arbitrary (Score:5, Insightful)
I think the most logical thing would be to consider "planet" a part of the name of a celestrical body, just like we do with "ocean" and "sea", and not use it as a classification word.
Re:Any definition is arbitrary (Score:2)
There are many ways they could classify planets which wouldn't be arbitrary at all. Base it on the minimum ammount of gravity it must have, and it's orbital path, and you have a non-arbitrary classification.
Unless I'm mistaken and you are trying to say that ALL classification is arbitrary, and classifying something like stars by how big and bright they are is equally "arbitrar
Re:Any definition is arbitrary (Score:3, Insightful)
This is not to say that calling anything anything is pointless. But it is pointless to invent a named category of objects if that category serves no other purpose than a placeholder for the name.
It would seem that in the case of
Give me a chance! (Score:2)
Re:Give me a chance! (Score:2)
There
Fine, but (Score:2)
It took them seven years... (Score:2)
Re:It took them seven years... (Score:5, Funny)
I now officially qualify for planethood.
Re:It took them seven years... (Score:2)
Re:It took them seven years... (Score:2)
Second, where is your source that Jupiter generates more radiant energy than it reflects?
my homebrew nomenclature (Score:5, Interesting)
planet = mostly rock/metal sphere with a significant atmosphere (what "significant" means becomes a point of contention then of course)
asteroid = solid rock/metal object that is not spherical
moon = rock/metal sphere without an atmosphere
a gas giant should be considered as something different than a planet (mostly gas, obviously spherical)... a star is simply a gas giant that has achieved thermonuclear fusion... and in between you have your brown dwarfs and other objects occuring at the end of a star's life time/ before it's lifetime/ malformed and never quite stars, etc.
and comets should also come to mean any agglomeration of ice and rock and dust that is loosely packed, not just those we see streaming towards the sun on a regular basis... as we explore the oort cloud, we'll find plenty of these "dormant" comets
and most importantly: all of these objects should be defined independently of what they orbit
so mercury isn't a planet, it's a moon of the sun
likewise, pluto is a moon of the sun
and ceres and vesta are moons of the sun (small perfectly spherical "asteroids")
titan isn't a moon, it's a planet of saturn (it has a significant atmosphere)
the most important thing i think, no matter what nomenclature is agreed upon, is that as we discover weirder extrasolar objects out there, the "what it orbits" part of an object's identity should come to mean something totally different than "what it's made of"
and size should never have meaning
then of course, we have to come to grips with direction of orbit, orbits outside the elliptical, orbits with bizarre shapes, binary/ tertiary objects, binary/ tertiary/ quartanery star systems, etc.
Re:my homebrew nomenclature (Score:2)
that's not a problem (Score:2)
nobody said anything about the need to capture the why of something being the way it is in a naming convention
you call something a "white dwarf", for example
you don't need to capture the idea it is a white dwarf because the star was not massive enough to supernova, that's not something you capture in the name of an object
you don't call it "whitedwarfleftoverfromdeathofstarthatwasnotbigeno ughtosupernova"
you don't say "thisisamoonnotaplanetbecauseitistooclosetothesunt ohavenaatmosp
Re: (Score:2)
Re:my homebrew nomenclature (Score:2)
First I would allow multiple planet systems.
If titan isn't a moon, but a planet of saturn I would rather call it a double planet system.
Second, size should matter, at least in some cases.
Otherwise a small speck of dust could be like a moon.
Third, I disagree with your "independently of what they orbit" remark.
I would like a moon to be changed to a planet when it stops orbiting somthing.
Fourth, what about rings versus asteroids?
Is the belt just rings of the sun?
Fifth, do rouge, no wai
Massaging the Data (Score:2)
I love western thinking (Score:2, Interesting)
Things are either black or white, up or down, good or bad. There are no shades of grey.
Can't we just say that there are different objects in the universe that have similar properties? What's wrong with saying an object is 30% like the planet we're on, but 70% like Jupiter?
Must everything have a category?
It's a real flaw in western thinking. We can't just simply let things be - we have to pin them to cork boards like preserved butterflies. Why not just describe what you find as you found it? Natur
Re:I love western thinking (Score:3, Insightful)
You can let things be all you want, I'd prefer striving to make things better.
Re:I love western thinking (Score:2)
We're arguing over whether Pluto is a planet or not.
That's the problem with that kind of fixed thinking - why can't we just say agree that nobody really knows and get on with actually learning stuff that's actually useful.
Re:I love western thinking (Score:2)
Re:I love western thinking (Score:3, Interesting)
Not going specifically for what's defined as "planets" feels like
Re:I love western thinking (Score:2)
Not going specifically for what's defined as "planets" feels lik
Re:I love western thinking (Score:2)
I noticed you categorized this as western thinking. That's rather boolean of you. Why not find the appropriate shade of gray and call it "thinking influenced by the scientific desire to categorize things?" The problem with complaining about black and white and suggesting shade of gray is that you're merely substituting one level of granularity for another. There is still a black and white.
The problem is _nouns_ themselves imply a need to categorize. We have star, plane
Importance of a definition (Score:4, Interesting)
Unless you are going to precisely define every single astronomical object [wikipedia.org]. from dust to galaxy filaments.
I suspect that someone is going to claim the possession over those planets (apply the definition here).
1 Earth = 1 Planet (Score:3, Interesting)
If an object is one half earth's mass, just call it 1/2 Planet. If the object orbits around a planet, just call it satellite or moon or subplanet. After all, planet means "to wander". What doesn't wander around the universe?
*Middle English, from Old French planete, from Late Latin planta, from Greek plants, variant of plans, plant, from plansthai, to wander.
ref. dictionary.com
Re:1 Earth = 1 Planet (Score:2)
Definition of a planet (Score:2, Funny)
"Not a star."
Re:Definition of a planet (Score:3, Funny)
Be careful man. Before you know it NASA has rovers rolling all over your ass.
Simplistic answer? (Score:2)
I know nothing about astronomy.
Wouldn't it be easiest to just state that anything that exists in the solar plane is a planet and anything that isn't is just a captured satelite?
I know that this would exclude Pluto and all other Ort Cloud objects.
This is a complicated question, but what is wrong with an easy answer?
Re:Simplistic answer? (Score:2)
Re:Simplistic answer? (Score:2)
So, how do we define "Solar plane" then?
1 degree either side of the plane of Earth's orbit? That includes Earth and Uranus.
2 degrees? Mars, Jupiter, Neptune get added.
3 degrees? Add Saturn.
4 degrees? Venus finally gets to be a planet.
7 degrees? Mercury joins the list.
We have to go out to 18 degrees to get Pluto on the list, but choosing 7 degrees is ju
I don't know what a planet is.... (Score:2)
But what I really want to know is this: planets orbit stars, and moons orbit planets, right? So what would you call something orbiting a moon?
Actually, I think we should have three categories: star, planet, asteroid. It shouldn't matter what it's orbiting. If it's big, round, and burning, it's a star. If it's big, round and not burning, it's a planet. If it's not so big and not so round, it's an asteroid. Luna, Ganymede, and Titan are both moons and planets. Phobos and De
a letter to iau (Score:4, Funny)
Missing the Point? (Score:4, Insightful)
Re:Missing the Point? (Score:2)
Isn't there a star in there, somewhere?
Surface Gravity (Score:3, Interesting)
This would also be useful as objects could be classed with a relevance that would be important to any future explorer. Even non elliptical objects could still be given a metric to judge their habitability.
"Sir, object is a Class G planetoid! Our noses will be crushed by our feet if we set foot on it."
"I see"
"However sir, the Halo Ring, despite not being isomorphic to a sphere, does qualify as a planet due to a reasonable average surface gravity."
"Cue music. We're going in.
But even dyson spheres could qualify as planets.
Three(ish) conditions (Score:4, Interesting)
Revolve around a star
within a certain maximum aphelion
having a maximum elliptic
Be large enough in volume
Not be artificial in nature (this provides that any intelligence in this universe creating an object that would fit the prior criteria would not be allowed to call it a planet)
Define maximum aphelion and maximum elliptic and minimum volume. What else is there?
Re:Three(ish) conditions (Score:2)
Re:Three(ish) conditions (Score:2)
Re:Three(ish) conditions (Score:2)
Re:Three(ish) conditions (Score:2)
Define artificial nature. The religious right would claim that all planets were created by an intelligent entity.
What about planets that formed on their own due to the creation of an artificial star?
What about planets that formed because the intelligent entity was so fricking huge that it accreted layers of debris via gravity, which compressed into rock from their own weight, reaching the required volume, but never intending
In other news... (Score:2)
The IAU has offered its Division III-Planetary Systems Sciences group $500,000 in the form of a promissory note if the definition sees commercial release by December 31, 2006.
Walking on the moon (Score:2)
Seriously, this entire "is Pluto really a planet" debate is getting very old. The word is just a word and no matter what you call Pluto it's still going to play the same role in our solar system. I can't believe that intellegent people with serious educations have a hair up their ass about simple terminology.
Re:Walking on the moon (Score:2)
Really, I mean who cares if its open source or free software. GNU/Linux or just Linux.
Pluto is a Planette. [TM], there problem solved. Pronounced the same so the teachers won't be wrong.
Re:Who cares? (Score:5, Interesting)
But seriously, what difference does life make? Any planet could support life if you put it in a habitat of some sort. Even gas giants could support life if said habitats floated (and yes, that hs been proposed - human breathable air is a lifting gas when the outside pressure is high enough). If you mean indigenous life, that's another story - we're very likely alone here in our solar system, so seeking to define a livable planet when we have exactly one example is a bit premature.
If you want to find examples of life outside our solar system, good luck. The best we can do currently is look for either signs of intelligence (which is SETI's business), or else look for a planet that shows signs of an oxygen atmospherem, since that would imply biological processes. We're already doing this IIRC.
And even then we'd be unable to show that a rocky body of the right temperature didn't have life - anaeorbic (sp?) life gets along just fine and dandy without toxic oxygen fouling up their enviroment. That doesn't even get into the possibility of life forms existing with completely different chemical composition, which we can't even make an educated guess about.
We couldn't even show that there isn't intelligent life somewhere, since there is no guarantee that they'd use the same methods of communicating as we do - all we can do is hope they're trying to contant us.
Re:Tangible? (Score:5, Insightful)
If you would, would mind explaining exactly how all our predictions based on those particles ended up being right? Lucky guesses, the lot of them?
That's an awfully big leap of faith.
Your comparison, by the way, entirely fails to hold water. The issue here is a historical mistake having been entrenched in the popular definition, and the lack of a technical definition. IUPAC doesn't have to deal with popular definitions confusing the issue, they're already developed technical definitions for anything within their scope.
Re:Tangible? (Score:5, Insightful)
Re:argument over definition of a word (Score:2)
Re:argument over definition of a word (Score:2)
"When I use a word," Humpty Dumpty said in rather a scornful tone, "it means just what I choose it to mean, neither more nor less." - Lewis Carroll.
Re:do not expect an intuitive definition (Score:2)
The reason for this is that the best clocks we have are based on exactly that transition. There's nothing comparable for the definition of a planet. And the exact number of periods was chosen to best fit the previous definition of the second.