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Space Science

Strange Mini Solar System Found 373

Posted by timothy from the that's-where-my-relatives-came-from dept.
starexplorer writes "In 1990, Penn State's Alex Wolszczan found the first exoplanets. But he never got much credit from mainstream researchers, because his planets (3 of them, roughly Earth-sized) orbit pulsars and hold no chance for harboring life. Now he's found a 4th object on the outskirts of the system, SPACE.com is reporting. Call it a planet, call it an asteroid, Wolszczan says, but call the setup a dark, eerie twin of the inner half of our solar system. Also in the same story, news of a brown dwarf just 15 times the mass of Jupiter that has a planet-making disk of stuff around it. Together, more problems for astronomers, who still don't have a basic definition for the word planet or a firm idea of what separates planets from stars."
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Strange Mini Solar System Found More

Strange Mini Solar System Found

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  • TMBG (Score:5, Funny)

    by angst7 ( 62954 ) on Monday February 07, 2005 @11:01PM (#11603700) Homepage
    I think They Might be Giants defined what it was to be a star fairly well.

    "The sun is a mass of incandescent gas
    a giagantic nuclear furnace..."

    • Re:TMBG (Score:3, Insightful)

      by Anonymous Coward
      The sun is a mass of incandescent gas
      A gigantic nuclear furnace
      Where hydrogen is built into helium
      At a temperature of millions of degrees

      Yo ho, it's hot, the sun is not
      A place where we could live
      But here on earth there'd be no life
      Without the light it gives

      We need it's light
      We need it's heat
      We need it's energy
      Without the sun, without a doubt
      There'd be no you and me

      The sun is a mass of incandescent gas
      A gigantic nuclear furnace
      Where hydrogen is built into helium
      At a temperature of millions of degrees

      The

      • Re:TMBG (Score:3, Funny)

        by Anonymous Coward
        Could you throw the extra apostrophes you put in the "it's" into the Sun? kthx bye

    • Re:TMBG (Score:3, Informative)

      by JabberWokky ( 19442 )
      TMBG didn't write that. It's a cover of an educational album.

      --
      Evan

    • " I think They Might be Giants defined what it was to be a star fairly well."

      Yes. It was a cover though. Science Songs [acme.com]. Check out "Why Does The Sun Shine" on the space album.

  • Superman (Score:3, Funny)

    by kevin-cs-edu ( 854636 ) on Monday February 07, 2005 @11:05PM (#11603719)
    "Call it a planet, call it an asteroid or call it Wolszczan says, but call the setup a dark, eerie twin of the inner half of our solar system." It's Bizarro world, our solar system's dark, eerie twin.

    • Re:Superman (Score:5, Interesting)

      by Rei ( 128717 ) on Monday February 07, 2005 @11:09PM (#11603746) Homepage
      I would love to see some of these extrasolar systems; the more we see, the more variety it looks like there is in the universe. "Hot jupiters" which orbit right close to their stars and even possibly exchange matter; the heat swells them up to many times their normal size. Brown dwarfs which give their closest moons enough light to possibly harbor life, while burning their deuterium slowly. Supercomets - planet-sized cometary bodies with huge comas. Planets without stars. "Water worlds" - bodies like Uranus or Neptune in a hotter orbit. And all sorts of other things.

      I hope some day humans can see them in person. :)

      • No wonder no one is trying to talk to us: We're boring! "Never mind that one FZKK, life could never develop there."
      • I could be wrong, but I thought that Neptune was a gas giant. This page [solarviews.com] seems to support that, but also seems to indicate that most of the planet is molten rock, water and similar stuff...

        • Re:Superman (Score:4, Informative)

          by SirBruce ( 679714 ) on Tuesday February 08, 2005 @04:44AM (#11604831) Homepage
          Uranus and Neptune, while they are gas giants, are much smaller and much further out than Jupiter and Saturn. As a consequence of this, their formation was much different. Instead of balls of mostly gas with a rocky core (at least, Jupiter had one initially even if it doesn't anymore), they are primarily huge many-Earth sized balls of ice and rock, which accumulated very thick atmospheres.

          They are probably a lot more like really big Titans than really small Jupiters. If they could be magically moved to the inner solar system, they would no doubt form huge oceans of water. But it would be difficult for such a planet to actually form that close to the sun in the first place with so much water.

          Bruce

    • Re:Superman (Score:3, Insightful)

      by LBArrettAnderson ( 655246 ) *
      I think most people have an over-obsession with how things are "defined."

      Together, more problems for astronomers, who still don't have a basic definition for the word planet

      I'm sure the astronomers simply don't care. It's not a problem; definitions don't change anything.

  • Planets from stars? (Score:5, Informative)

    by hobbesmaster ( 592205 ) on Monday February 07, 2005 @11:07PM (#11603732)
    Someone please correct me if I'm wrong or over generalizing, but planet vs stars: stars have fusion, planets dont. Hence, a gas giant like jupiter is a planet but a brown dwarf is a star (there is SOME fusion going on, or there was in the past).

    Planet vs planetoid is another matter altogether... I'd love to know if theres been a 'real' standard proposed - regardless of whether pluto/charon are planets/moon or not.

    • Re:Planets from stars? (Score:5, Informative)

      by Scott7477 ( 785439 ) on Monday February 07, 2005 @11:14PM (#11603775) Homepage Journal
      As far as a definition I found this:

      "Working Group on Extrasolar Planets
      Defintion of a "Planet"

      POSITION STATEMENT ON THE DEFINITION OF A "PLANET"

      WORKING GROUP ON EXTRASOLAR PLANETS (WGESP) OF THE INTERNATIONAL ASTRONOMICAL UNION

      Created: February 28, 2001

      Last Modified: February 28, 2003

      Rather than try to construct a detailed definition of a planet which is designed to cover all future possibilities, the WGESP has agreed to restrict itself to developing a working definition applicable to the cases where there already are claimed detections, e.g., the radial velocity surveys of companions to (mostly) solar-type stars, and the imaging surveys for free-floating objects in young star clusters. As new claims are made in the future, the WGESP will weigh their individual merits and circumstances, and will try to fit the new objects into the WGESP definition of a "planet", revising this definition as necessary. This is a gradualist approach with an evolving definition, guided by the observations that will decide all in the end.

      Emphasizing again that this is only a working definition, subject to change as we learn more about the census of low-mass companions, the WGESP has agreed to the following statements:

      1) Objects with true masses below the limiting mass for thermonuclear fusion of deuterium (currently calculated to be 13 Jupiter masses for objects of solar metallicity) that orbit stars or stellar remnants are "planets" (no matter how they formed). The minimum mass/size required for an extrasolar object to be considered a planet should be the same as that used in our Solar System.

      2) Substellar objects with true masses above the limiting mass for thermonuclear fusion of deuterium are "brown dwarfs", no matter how they formed nor where they are located.

      3) Free-floating objects in young star clusters with masses below the limiting mass for thermonuclear fusion of deuterium are not "planets", but are "sub-brown dwarfs" (or whatever name is most appropriate).

      These statements are a compromise between definitions based purely on the deuterium-burning mass or on the formation mechanism, and as such do not fully satisfy anyone on the WGESP. However, the WGESP agrees that these statements constitute the basis for a reasonable working definition of a "planet" at this time. We can expect this definition to evolve as our knowledge improves."

      It looks like this is as close as we're going to get.

    • Re:Planets from stars? (Score:5, Informative)

      by Rei ( 128717 ) on Monday February 07, 2005 @11:16PM (#11603795) Homepage
      It's not that simple. Do you say "If there was ever a single Dt-Dt reaction, it's a star", or do we require continuous reactions? It's hard to put an exact cutoff on the sequence from planets to main sequence stars.

      All of the bodies get some heat from gravitational collapse as they condense. Once you get enough heat and pressure in a small enough area, you can get Dt-Dt fusion; when there is a "significant" amount, it's called a brown dwarf. However, a relatively small amount of hydrogen is deuterium. As it gets hotter and denser, you begin to get other types of fusion, and you end up with a main sequence star.

      The planet/moon distinction becomes even harder when you can't tell exactly what's a planet or star. Once we get to some of these "huge jupiters", there will undoubtedly be debates as to whether there is a measurable amount of Dt-Dt fusion going on or not.
      • "Do you say "If there was ever a single Dt-Dt reaction, it's a star", or do we require continuous reactions?"

        If you were to say so, then the Earth is a star by that definition. Some of the more complex electrochemical reactions taking place there have resulted in a number of Dt-Dt reactions in the past century or so.
      • "Do you say "If there was ever a single Dt-Dt reaction, it's a star", or do we require continuous reactions?"

        *Tap Tap* I think my babel fish is getting old.

    • The definitive definition (Score:5, Insightful)

      by Profane MuthaFucka ( 574406 ) <busheatskok@gmail.com> on Monday February 07, 2005 @11:28PM (#11603861) Homepage Journal
      A planet:
      -is a non-fusor
      -has sufficient mass to be roughly spherical due to gravity
      -orbits a fusor
      -isn't already referred to as any other type of object by convention
      -isn't associated through orbital composition or other general characteristics with another general group of non-planet objects (i.e. Vesta, though spherical, is associated with other objects known as asteroids, which are not massive enough to be spherical, and are therefore not planets. Vesta also is not a planet, because of the previous rule. It is by convention known as an asteroid, therefore it's not a planet.)

      My source for this definition is myself, and I deem it sufficient for sparking a major discussion, and possibly for other things as well.
      • -has sufficient mass to be roughly spherical due to gravity

        Not sure if that would work. I could imagine a binary star system with a planet in between them as such with an erratic orbit that causes it to be stretched in an extremely egg shaped way.

        It might need to be a more than binary star system to keep balance. IANAA.
        • Such an object would cease to exist, spiraled into one star or another, long before a human got around to figuring out what to call it. Taxonomy is a *descriptive* science. I demand that you only describe objects that actually currently exist before you start naming the numerous figments of your imagination!
      • Just as long as you aren't claiming exclusivity. A fusor can orbit a fusor after all, making neither a planet, just pointing out that orbiting a fusor by itself doesn't mean much. Could a black hole be considered a fusor?
      • so what do you call a spherical non-fusor that orbits a brown dwarf (eg a non-fusor)?

    • Note that it is possible to have very large planets that do not have fusion as you describe but have such a large volume to surface area that they retain heat for a long time. That heat may be enough to actually make the planet glow like a star and warm a retinue of moon-planets. It would look like a dim star. I'd agree it is a planet but that that doesn't mean it cant have its own lifebearing worlds.

  • Mini solar system (Score:5, Insightful)

    by Scott7477 ( 785439 ) on Monday February 07, 2005 @11:07PM (#11603735) Homepage Journal
    How can this professor not be considered mainstream?
    He's on the faculty at Penn State! Sounds like he must have ticked off the wrong people at some point in his career. Maybe he needs to hire a PR person.
    I would say that finding a planet orbiting any star would be significant news, regardless of whether said planet might harbor life.

  • semantics (Score:5, Informative)

    by Anonymous Coward on Monday February 07, 2005 @11:07PM (#11603736)
    semantics seperates planets from stars from asteroids... Our language, not reality...

  • Planet Definition (Score:5, Funny)

    by FiReaNGeL ( 312636 ) <.moc.liamtoh. .ta. .l3gnaerif.> on Monday February 07, 2005 @11:07PM (#11603739) Homepage
    Astronomers don't have a planet definition? Here's one! Planets are round, asteroids aren't! How's that ? :)
    • http://dictionary.reference.com/search?q=planet At the very least, we could be using: "A nonluminous celestial body larger than an asteroid or comet, illuminated by light from a star, such as the sun, around which it revolves." Then you have the matter of size. A moon would be a natural planet satellite.

  • Definition (Score:5, Funny)

    by null etc. ( 524767 ) on Monday February 07, 2005 @11:08PM (#11603741)
    ...or a firm idea of what separates planets from stars.

    Space. Quite a bit of it, I hope.

    Oh, you meant what criteria separates planets from stars?

    Well, I definitely would much rather live on one than the other. Is that a good definition?

  • Star vs Planet (Score:3, Interesting)

    by imemyself ( 757318 ) on Monday February 07, 2005 @11:09PM (#11603749)
    Would a star not be any object that makes light on its own(ie, not reflects it)? IANAA(Astronomer)

    • Stars generate energy (Score:5, Informative)

      by Man in Spandex ( 775950 ) <prsn@kev.gmail@com> on Monday February 07, 2005 @11:19PM (#11603807)
      At least according to Wikipedia [wikipedia.org]

      Scientifically, stars are defined as self-gravitating spheres of plasma in hydrostatic equilibrium, which generate their own energy through the process of nuclear fusion.

      Using this simple definition, it seems to apply to most stars out there? Correct me if I'm wrong or if the definition provided isn't accurate enough.

      • Re:Stars generate energy (Score:5, Informative)

        by YU Nicks NE Way ( 129084 ) on Monday February 07, 2005 @11:35PM (#11603892)
        That works quite well for objects above about 25 Jovian masses. (In isolation, yadda yadda yadda) At that size, the body is large enough to support sustained thermonuclear fusion of species other than D+D->He3. Such bodies quickly heat up, becoming true red dwarf stars.

        Object smaller than about 13 Jovian masses never exhibit any sustained fusion. Those objects are planets if they orbit a star or a stellar remnant. (They are "sub-brown dwarfs" if they don't orbit a star.)

        Objects that sit between the 13 and 25 Jovian mass boundaries are in a grey area. They do exhibit sustained fusion, but only of D+D pairs. There isn't much deuterium around, though, so they don't ever heat up very much. Moreover, since they never engage in H+D->T and H+T->He3 fusion, they don't engage in the fusion reactions which are the signature of "real" stars. These are brown dwarfs -- not planets, because they do heat themselves up with fusion reactions, but not stars, either, because they don't fuse H.

    • Re:Star vs Planet (Score:3, Insightful)

      by kf6auf ( 719514 )

      Let me start by saying that our star's light (electromagnetic radiation) peaks in the visible region of the spectrum (which is why we evolved to be able to see it). This energy comes from nuclear fusion (usually Hydrogen/Deuterium/Tritium -> Helium; it's complicated and you can look it up if you want).

      So why doesn't this definition work? Because planets emit their own light too; and I don't mean reflection or reemission. Take Jupiter for example. It's big right? If you dropped a ton of stuff into

  • Credit (Score:2, Funny)

    by prakslash ( 681585 )
    At the 1990 Astronmy Conference.. And.. we would like to give credit to Mr. Wolz.. uhh.. Mr. Wolzz.. Mr. Wolzczka.. Aww. screw it.

  • No chance of life? (Score:5, Interesting)

    by suso ( 153703 ) on Monday February 07, 2005 @11:10PM (#11603756) Journal
    because his planets (3 of them, roughly Earth-sized) orbit pulsars and hold no chance for harboring life.

    I wish people wouldn't say things like this. Humans barely have a grasp on what life really is and what conditions it can exist under, especially off our own planet. So how could we make a judgement that life couldn't exist around a pulsar, despite its homo-sapien threatening conditions.

    • Re:No chance of life? (Score:2, Informative)

      by canb ( 792889 )
      Acutally there are only two forms of life possible. Carbon based like our world or silicone based. And we know a lot about carbon based lifeforms and under what conditions it can be formed. It is even possible to create carbon based organic matter from inorganic when early earth conditions are recreated. These protoplasmas attach and under heavy radiation from the sun, genetic diversity forms and the rest is evolution. As for silicone based life forms, silicon-oxygen bond is much stronger than carbon-hydro
      • "Carbon based like our world or silicone based."

        Wow, so that explains the fact that virtually all female aliens, whether carbon or, er, silicone-based have large, prominent chest-bumps...

      • Re:No chance of life? (Score:5, Funny)

        by vwjeff ( 709903 ) on Tuesday February 08, 2005 @12:10AM (#11604051)
        Acutally there are only two forms of life possible.

        According to whom?

        The only life we can be certain of is our own. Even then I sometimes wonder if I really exist. I guess I must because I am posting this, or am I?
      • Homer: I'd like to answer any questions regarding the alien, any questions at all.
        Dr Hibbert: Yes. Is the doctor carbon based or silicon based?
        Homer: Uhhh, the second one, Zillifone.
    • Humans barely have a grasp on what life really is and what conditions it can exist under, especially off our own planet.

      Like this species of worm [wikipedia.org] found less than a year ago on our own planet. We have no idea what could be out there.

  • Smallest planet (Score:2, Interesting)

    by maglor_83 ( 856254 )

    From the article:
    In one of the discoveries, an object just one-fifth the size of Pluto was called the smallest planet ever found outside our solar system

    If it's one-fifth the size of Pluto, wouldn't that make it the smallest planet ever found anywhere?

    • You assume Pluto is a planet. That's where a lot of this controversy stems from. There are many suggestions for what makes a planet and Pluto often falls outside of the definition. If Pluto is reclassified as a moon or extra solar space junk, then this "Smallest planet" probably would be as well.

  • How insensitive! (Score:5, Funny)

    by Anonymous Coward on Monday February 07, 2005 @11:15PM (#11603786)

    ..a brown dwarf just 15 times the mass of Jupiter..

    Please, "African American little person with a weight problem" is a little more appropriate and a lot less offensive, don't you think? Sheesh.

  • Well Obviously (Score:5, Funny)

    by Madcapjack ( 635982 ) on Monday February 07, 2005 @11:15PM (#11603789)
    Well Obviously this old dying star system is the original home of our species. We're just the descendents of the marooned colonists who found that their pyramid space-ships had suddenly (and quite inexplicably) turned to stone.

    Go figure.

    • Well Obviously this old dying star system is the original home of our species. We're just the descendents of the marooned colonists who found that their pyramid space-ships had suddenly (and quite inexplicably) turned to stone.

      Over-rated I can understand. But flame-bait? Did I offend the foil-hats?

  • I am picturing... (Score:3, Funny)

    by spankey51 ( 804888 ) on Monday February 07, 2005 @11:25PM (#11603843)
    A small gathering of Mini Coopers around a campfire in europe... Or something...
  • It's all a matter of size. Stars have enough mass to begin fusion. Planets have enough mass to become 'round' and orbit a star. Asteroids orbit stars but aren't 'round'. Moons orbit planets and are 'round'. Blah blah blah. So on and so forth. It's bloody easy. Man.. I should be an astrophysicist!

  • Why on Earth does the name matter? (Score:5, Interesting)

    by TechyImmigrant ( 175943 ) * on Monday February 07, 2005 @11:38PM (#11603913) Homepage Journal
    We started out with a limited number of names for things. Planets, stars, the sun. They we found some more things like comets and asteroids.

    Now we've found lots of things that come in between, requiring a different form of classification. The only problem is that people are trying to squeeze the definition of things we know about into a limited naming set.

    To name something doesn't mean we understand it and being unable to name something doesn't mean we don't understand it.

    People should stop worrying and be happy that we can describe these objects to a higher level of detail than can be described using the existing names we had for things floating in space.
  • "who still don't have a basic definition for the word planet or a firm idea of what separates planets from stars."


    One is on fire and one isn't.

    Now hand over my research grant.
  • Well, I am glad to know that our astromomers are idiots. Makes me feel better.

    The term "mini solar system" is wrong. Solar -the word- is derived from Sol, the name of that thing we call "the sun" (cue CD7 joke about Sun, long a source of amusement) aka that great big yellow ball thing.

    It is Sol. If you didn't know it had a name, blame your teachers.

    Our happy family of planets is the Solar System. Because we all belong to Sol. There is one Sol and one Solar System in the entire universe.

    This newly d
    • All your sol-ar belong to us?

      sorry

  • It shouldn't be that hard. (Score:5, Interesting)

    by Corbin Dallas ( 165835 ) on Tuesday February 08, 2005 @12:21AM (#11604100) Homepage
    problems for astronomers, who still don't have a basic definition for the word planet or a firm idea of what separates planets from stars.

    It's not as sexy as having a word like "planet", but all this confusion could be eliminated with a basic classification system that took into account distinguishing characteristics besides just it's mass.

    As an example, one could define these objects through two primary attributes: The body's mass and the mass of that which it orbits. As I don't have exact mass data at hand, this example will use the following over-simplifications:

    S = Solar Mass
    G = Gas Giant Mass
    R = Rock Planet Mass
    M = Minor Mass ( appx Phobos to Pluto )
    A = Asteroid Mass
    D = Debrit ( 1m or smaller )

    Of course, the real system would use exact scientific measurments rather than these crude examples.

    Earth = SR ( Rock Planet Mass orbiting a Solar Mass )
    Jupiter = SG ( Gas Giant Mass orbiting a Solar Mass )
    Pluto = SM ( Minor Mass orbiting a Solar Mass )
    Titan = GR ( Rock Planet Mass orbiting a Gas Giant Mass )
    etc
    etc

    You could even create a symbol to represent the galactic center, which could be used in relation to stars and other free roaming bodies. Binary stars can be represented using SS, since they're orbiting each other.

    Anyway, the point is that you can not come up with solid definitions of these bodies on mass alone. Take into account other major factors as this example does.

  • brown dwarf (Score:2, Funny)

    by boaboy ( 319727 )
    Also in the same story, news of a brown dwarf...

    My God, man! An oompa loompa!

  • Always labeling things.
  • I don't know about you and I don't care what you tell me but when I look up I see a bunch of stars and a really big one that my family named the Moon. When I look down I see a planet. In the daytime I see a Sun. My formal definition:
    Stars are bright at night and Sun(s) are bright during the day.
  • mercury, to me, is a moon orbitting the sun

    titan, to me, is worthy of being considered a planet on the same level as earth or venus

    and then there are gas giants, stars, and all the little bits (comets, asteorids, etc.)

    so to me, phobos and deimos are not moons: they are still asteroids, they just happen to orbit mars instead

    and i really believe considering the characteristics of the object separately from what it orbits is way more important

    our current nomenclature seems obsessed with what an object orb

  • Hmm... What makes a planet? (Score:3, Insightful)

    by The Master Control P ( 655590 ) <ejkeever@nerdshac[ ]om ['k.c' in gap]> on Tuesday February 08, 2005 @01:21AM (#11604308)
    Pulling together some suggestions seen in other threads with my own thoughts:

    A star: Generates energy by sustained, large-scale fusion reactions.
    A brown dwarf: A 'failed' star with less than the minimum mass necessary for sustained large-scale fusion, but enough to generate either minimal fusion reactions or to glow by the energy of it's slow gravitational contraction. To be honest, I can't think of any non-arbitrary distinction between a brown dwarf and a large gas giant, just as there is a continuous spectrum between a centrally-planned and free-market economy.
    A planet: Is massive enough to form itself into a sphere or ellipsoid and orbits a star in a stable orbit uniquely it's own (ie is not shared with other orbiting bodies, and is circular or some semblance thereof).
    A moon: A natural satellite that orbits a planet in an orbit uniquely it's own (re: is not a ring particle).
    An asteroid: An object, not any of the above, that orbits a star and does not contain significant deposits of volatile compounds.
    A comet: An asteroid that does contain significant amounts of volatile compounds.

    By my system, Ceres is an asteroid, because it does not have it's orbit to itself. Pluto is a planet because it can pull itself into a sphere, and possesses it's own (admittedly rather elliptical) orbit. The KBOs are all asteroids or dormant comets, because they either lack the mass to shape themselves or share orbits with other KBOs.

    • Strictly the speaking, Earth and the Moon are pretty much dual planets (their common center of gravity lies in between them, for instance). When you plot their orbits around the sun, they're very similar, just wobbling around each other twelve or so times per orbit - that's not so much.

      Which would make them asteroids in your system, I think.

  • ..."what separates planets from stars."

    ME: Hey professor! What separates planets from stars?

    PROFESSOR: Space. Or about 2,500 to 50,000 Kelvin.

    ME: Thanks professor!

  • Maybe a brown dwarf is just still a star in training? It just didn't get fed enough as a kid, but it could have hope someday, couldn't it? It's so cruel to just label it "failed" and leave it in misery... It could get a job on the set of a sci-fi show or something, you never know.
  • I think we should define a planet as a celsestial body that can support multi-organism life.

    otherwise it's an asteroid, comet, celestial body, whatever.

    would that mean that this solar system doesn't have 9 planets? yes it would. it doesn't change the fact that we still have 9 celestial bodies in the vicinity.

    Why are we trying to hang on to old definitions that don't make sense? Because our ancestors used them? Advance, make progress people.
  • If bruce willis is trying to protect it...it's a planet.

    If he's trying to blow it up...it's an asteroid.

    If you wish you could throw him into it and watching him vaporize...it's a star.

    I call it the willis theory of astronomy

    (movies stars...is there any problem they can't solve?)
  • I was sure that was historically settled. Stars shine. Planets reflect. And that's all. Who needs anything more?
  • Lame. I want a solar system shuffle.

  • Leave differentiation to the experts? (Score:3, Interesting)

    by Meetch ( 756616 ) on Tuesday February 08, 2005 @03:16AM (#11604641)
    Looking here, I see lots of what I would normally consider insightful input into what could be eventual definitions of stars, supergiants, planets, asteroids and pebbles. However, as was mentioned the definitions are simply going to have to evolve with our understanding.

    Would The Earth cease to be a planet just because something threw it forever out of our solar system? (Well actually, for now almost certainly yes, 'cos then there'd be no humans to define "planet" ;). At what point does an asteroid have to collect enough dust and become spherical enough to become a planet? Not all planets are spherical - Mercury is more elliptical from memory, thanks to effects of being in close proximity to a star... errr, the Sun. They wouldn't even have to necessarily spin - though that would help with roundness.

    Also from recollection of earlier dictionaries, our moon would become a planet (or planetoid?) if some catastrophe yanked it away from the earth, to forever go around the sun - because it wouldn't then be a body orbiting a planet - a simple, but rock solid definition IMHO. Oh but hang on, what about all those little rocks orbiting Earth???

    In that respect remember that some definitions are probably inherently transitional, depending on what they are doing. If it's a rock orbiting a sun, it's an asteroid, around a planet then it's a moon, if it's become round (has enough gravitational pull to hold itself together?) then it's a planet if it's going around a Sun - or is it, because what if the planet escapes?

    I believe the dictionary definition of "moon" is pretty good already, but as for the rest... I hope you can see what I mean because it gives me a headache! If we set a strict definition of a type of celestial body, and then suddenly we discover that there are so many more bodies that just don't quite fit the category, then what? I don't fancy taking liquid paper to my dictionary. So I will leave splitting those hairs to the experts.

  • Definition (Score:5, Funny)

    by GrabtharsHammer ( 852908 ) on Tuesday February 08, 2005 @03:28AM (#11604666)
    planet n.
    Big lump of stuff, roundish, spinning a bit, usually orbiting a, um, star thingy. Might have aliens on, but probably not. Probably.

  • No Lables. (Score:3, Interesting)

    by jellomizer ( 103300 ) * on Tuesday February 08, 2005 @07:16AM (#11605181)
    Together, more problems for astronomers, who still don't have a basic definition for the word planet or a firm idea of what separates planets from stars.

    It is rather funny how we humans need a way to pigeon hole everything we observe. And the more we observe the more pigeon holes we need to add. The universe didn't come with labels and many things are don't neatly fall in to a area. I think we have forgotten that language is created by humans and can and should be expanded to explain new things we observe. Maybe english needs a word that explains objects in less of a pigeon hold method and more of a gradient scale. I will use say we use the word. "blong" for something is more then something else like "Jupiter is planet blong star", quaz for something that is in the middle "Pluto is planet quaz asteriod"

    • Objection! (Score:3, Funny)

      by serutan ( 259622 )
      I am Blong, of the Quaz nebula. By using my name without permission you have violated galactic copysnark law. Your puny planet will be destrobulated in 65 metrons.

  • In Japanese (Score:3, Informative)

    by dirtsurfer ( 595452 ) on Tuesday February 08, 2005 @09:37AM (#11606052) Journal
    the word "hoshi" means both planet and star.

    So we live on a hoshi, and all the bright things you see in the sky are also hoshi's.

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