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New Moon of Jupiter Discovered

Posted by CowboyNeal on from the heavenly-bodies dept.

xihr writes "Astronomers have discovered a new moon of Jupiter, bringing its known retinue of satellites to a whopping 40. The new moon, designated S/2002 J1, is only 3 km wide, and has a highly inclined and eccentric orbit. Astronomy.com has the story."

68 of 152 comments (clear)

  1. Questions by MattC413 · · Score: 5, Interesting

    Only 3 km wide? At what point does it go from being a relatively small chunk of rock floating around a planet to being a moon?

    Would it be possible haul enough of a mountain into space orbit to be technically classified as a moon? I mean, man has walked on Earth's moon.. but is he able to make one himself? Or has he already?

    -Matt

    1. Re:Questions by p4ul13 · · Score: 5, Informative
      I think you're slightly off the mark there.

      Anything orbiting a planet is a satelite, but not every satelite is considered a moon.

      --
      Paul Lenhart writes words!
    2. Re:Questions by Anonymous Coward · · Score: 2, Funny

      If it is made from green cheese, it is a moon. If it is made from rock (or pixels), it is an asteroid.

    3. Re:Questions by slipgun · · Score: 2

      unless you're an astronomer, in which case they're all metal

      Could you elaborate on this, please?

      --
      SpamNet - a spam blocker that really works
    4. Re:Questions by Daniel+Dvorkin · · Score: 2

      Seriously, it does seem to be a bit silly to call something this small a moon, especially relative to Jupiter, which has several moons worthy of the name. IMO we should set (completely arbitrary, yes) lower limits on what we call both planets and moons:

      1) If it freely orbits the Sun (or some other star, which is now becoming more than an academic distinction), and it's Pluto-size or larger, it's a planet. (To get rid of the "Pluto is not a planet" silliness.) Otherwise it's an asteroid, a comet, a Kuiper belt object, whatever.

      2) If it orbits a planet orbiting the Sun (or some other star, etc.) and it's either a) larger than Phobos or Deimos (whichever is smaller, I forget) or b) larger relative to the planet it orbits than min(Phobos,Deimos) is relative to Mars, then it's a moon. Otherwise, it's a captured asteroid, or a microsatellite, or whatever. And yes, this means Earth only has one moon, and will for some time, until we build a space station larger than min(Phobos,Deimos) -- which will be a while, I gloomily suspect.

      Like I said, this is completely arbitrary, but it has the advantages of both retaining historical classifications and satisfying the original version of Occam's razor. (Don't multiply entities unnecessarily.) There's a lot of stuff floating around the Solar System, and we're finding more all the time. How many damn planets and moons do we really need? ;)

      --
      The correlation between ignorance of statistics and using "correlation is not causation" as an argument is close to 1.
    5. Re:Questions by MoreDruid · · Score: 2, Interesting

      Earth has one natural moon, and many thousand artificial satellites.
      this is debatable, as astronomers have yet to agree on what a moon is.

      --
      The best weapon of a dictatorship is secrecy, but the best weapon of a democracy should be the weapon of openness.
    6. Re:Questions by Simon+Field · · Score: 5, Interesting


      Astronomers and cosmologists use the term "metal" as a shorthand for anything other than hydrogen and helium.

      --

      Free book: Science Toys You Can Make

    7. Re:Questions by Hentai · · Score: 3, Interesting

      Which is kinda wacky, considering that - chemically - Hydrogen behaves as a 'metal' (in the classical sense) in certain circumstances, and the other nobles (neon, argon, etc.) will NEVER behave as anything other than a noble (well, except xenon, but once you get that much separation from your orbital field and your nucleus, all bets are off.)

      Just goes to show that even scientists can fall into the trap of ambiguous contextual terminology. It'd be nice to go through and create a single, agreed-upon, interdisciplinary scientific language, where when you talk about something, everyone knows what you're saying. (While we're at it, let's set the speed of light to 1 and try and normalize as many fundamental constants as possible.)

      --
      -Hentai [in vita non pacem est]
    8. Re:Questions by Hentai · · Score: 5, Informative

      Actually, even better:

      If it freely orbits a star, is IN THAT STAR'S PLANE OF THE ECLIPTIC, it's a planet (note: this knocks Pluto off the list). You still need some arbitrary limits here, though: I'd say as long as the normalized dot product of the orbit's normal vector with the plane of the ecliptic is within four sigma, you can call it a planet (note - don't take the absolute value - if it's going the wrong way, it's not a planet). Interestingly enough, this places most of the asteroids in 'planet' status.

      That pretty much limits planets to objects which were clearly formed from the accretion disk of the star, as opposed to 'leftover junk' (which something like Pluto most assuredly is). Of course, this also means that a planet can get knocked out of its original orbit, and lose its 'planet' status, but this is also an acceptable side-effect if you want definitional consistency.

      For 'moon', any body which orbits a planet within two sigma of ITS plane of ecliptic should be considered a 'moon'. Here we need a good definition of 'orbit' - if, at any time, an object's orbit brings it *away* from the center of mass of its solar system, and towards its planetary primary, it's in orbit around that planetary primary, and not its star. This means, incidentally, that the Earth's Moon is not a moon - it's another planet that happens to co-orbit the sun within the same boundry space as the Earth, and the two planets perturb each other's orbits.

      Any body which does not fall under this criteria is a 'satellite' of its primary, but not a 'planet' or 'moon'.

      While this definition leads to a few counter-intuitive situations (or at least, counter-traditional), that's inevitable when formalizing terminology. People use words too loosely to expect all possible cases to fit the 'traditional' nomelcatures, so when formalizing, you sometimes have to accept a few deviances (for example, if we were to normalize biological taxonomy, dogs, wolves, coyotes, and jackals would all be the same species - since they're genetically capable of interreproducing. It's only weight of tradition that keeps them seperate, a very unscientific concept.)

      --
      -Hentai [in vita non pacem est]
    9. Re:Questions by Zontar+The+Mindless · · Score: 3, Insightful

      Actually, many astronomers consider the Earth-Moon system to be a double planet.

      --
      Il n'y a pas de Planet B.
    10. Re:Questions by ottffssent · · Score: 2

      Technically, "Moon" is the proper name for Earth's major satellite. In common usage though, a moon is any natural satellite of a planet. I have been unable to find specific requirements as to size of satellite, eccentricity of orbit, stability of orbit, etc. which would cause random bits of debris, such as those making up Saturn's rings, to be classified as moons or not.

      My personal criteria would require uniqueness and stability. That is, tiny rocks in a ring are not unique, whereas a single (or two, or 40) orbiting body deserves special recognition. Also, the orbit must be stable. That is, an asteroid captured by a planet's gravity in an orbit that will smash it into something in 200 years is not a moon. It is a pet.

      --
      High-speed Road Trip (18.000KPH)
    11. Re:Questions by Animats · · Score: 2
      Would it be possible haul enough of a mountain into space orbit to be technically classified as a moon?

      When will we have the technology to make that a serious question? Not this century, at the rate we're going.

      For what it's worth, international law is that you can't create or expand a country by building an island. If the island isn't naturally above water at high tide, it doesn't count. One of Japan's boundaries depends on a tiny island a few meters across, and to keep it from wearing away, which would cost Japan fishing rights, a breakwater has been built around it.

    12. Re:Questions by Jeff+DeMaagd · · Score: 2

      As for an offician name for Earth's companion, how about Luna? That's what I thought it was to a number of scientists.

    13. Re:Questions by Jeff+DeMaagd · · Score: 2

      Astronomers and cosmologists use the term "metal" as a shorthand for anything other than hydrogen and helium.

      Why am I not surprised?

      Heck, I think physics and chemistry has two opposing views on electron charge flow, and electrical engineering holds that both are true. It's pretty frustrating to deal with this sort of crap.

    14. Re:Questions by podperson · · Score: 2, Insightful

      Here we need a good definition of 'orbit' - if, at any time, an object's orbit brings it *away* from the center of mass of its solar system, and towards its planetary primary, it's in orbit around that planetary primary, and not its star. This means, incidentally, that the Earth's Moon is not a moon - it's another planet that happens to co-orbit the sun within the same boundry space as the Earth, and the two planets perturb each other's orbits.

      This seems to be a bad and ambiguous definition and an erroneous interpretation of that definition.

      1) It's circular. You definite orbit in terms of orbit.

      2) The Earth is, at some point in its orbit, moving closer to the Moon and away from the sun, ergo it is the Moon's moon. And vice versa.

      3) The Earth is, at some point in its orbit, moving closer to Neptune and away from the Sun, ergo it is Neptune's moon.

      Surely the simple criterion is along the lines:

      1) if we can see A moving around B and C, and we were to remove the influence of C, and then A continues around B, A is orbiting B -- if they would just fly off to infinity (or otherwise approximate a hyperbolic orbit) then A is not orbiting B.

      2) if A and B satisfy condition 1, then we say A orbits B if A is (some degree of our choosing) less massive than B. If they are within (some degree of our choosing) we say they orbit each other.

    15. Re:Questions by Hentai · · Score: 2

      Thank you. That's what I MEANT to say, but I had a major semantic subsystem glitch about halfway through. Sorry about the obviously bogus definition of 'orbit' I posited.

      --
      -Hentai [in vita non pacem est]
    16. Re:Questions by Idarubicin · · Score: 2
      While we're at it, let's set the speed of light to 1 and try and normalize as many fundamental constants as possible.

      This is already done--sort of--in quantum mechanics. Most problems can be restated in so-called atomic units where the electron charge is -1, Planck's constant (h-bar) is 1, the electron's mass is 1, and the unit length is the Bohr radius (a_nought). The unit of energy becomes the hartree, equal to e^2/a_0, which is 1 in this new system. Anyone who does much in the way of computational chemistry works almost exclusively in these units to get rid of all the messy conversions and constants.

      Unfortunately, in atomic units the speed of light c is equal not to 1 but to the inverse of the fine structure constant alpha. Though this makes c a more manageable 137 (roughly) it's not quite down to one. Besides, these units aren't particularly useful on a human scale.

      Upon further investigation, I should note that some astronomers and cosmologists do set c to be exactly 1. They also make use of such handly length scales as light-seconds. Erm.

      It took decades to gain near-universal acceptance of the metric system, despite its advantages. Indeed, there still exist one or two backward nations that refuse to adopt SI. How do you propose we convince people to accept a system where the posted highway speed limit will be on the order of 0.0000001?

      --
      ~Idarubicin
    17. Re:Questions by ceejayoz · · Score: 2

      Officially...

      Earth = Terra
      Moon = Luna
      Sun = Sol

      but most people just use the common names.

    18. Re:Questions by Animats · · Score: 2
      So what happens when the ice melts and the mean ocean level rises?

      Unclear. Historically, boundaries follow nature. Many rivers wander, and international boundaries that follow rivers sometimes move with the river.

      Ocean level vs. land level is a complicated subject. Land level isn't constant; it changes slightly with crustal movement. This vertical movement, over a century or so, can be substantial. It makes long-term tide data an unreliable measure of ocean level. See this article.

    19. Re:Questions by zCyl · · Score: 2

      The bottom line is that for astronomers to do their jobs, they don't need any reformation of current classification systems. It doesn't matter what you call the bodies in question; whether you call Pluto a planet, an asteroid, or a Kuiperoid doesn't change anything about its inherent nature. It's worth pointing out that pioneering such reclassifications is restricted almost entirely to amateurs, for the simple fact that the professionals don't care.

      You must be new to the greatest of all scientific strivings: funding.

  2. I think we should steal it. by drfishy · · Score: 5, Funny

    Lets take that moon into earth orbit, it could be fun.

  3. By Jove!!! by digitalsushi · · Score: 5, Funny


    By Jove, another moon!

    runs away quickly

    --
    slashdot: where everyone yells sarcastic metaphors to themselves to understand the issue
  4. Old Joke... by Cyno01 · · Score: 5, Funny

    Thats no moon, its a space station!

    --
    "Sic Semper Tyrannosaurus Rex."
  5. Re:Would be fun to live on jupiter.... by Cyno01 · · Score: 2

    Yeah, and being reduced to a pile of goo a few centimeters thick by the jovian gravity, good times.

    --
    "Sic Semper Tyrannosaurus Rex."
  6. Stupid name... by PontifexPrimus · · Score: 5, Informative
    To quote from A. O. Prickard (tr.), "The `Mundus Jovialis' of Simon Marius," The Observatory 39(1916):
    Jupiter is much blamed by the poets on account of his irregular loves. Three maidens are especially mentioned as having been clandestinely courted by Jupiter with success. Io, daughter of the River, Inachus, Callisto of Lycaon, Europa of Agenor. Then there was Ganymede, the handsome son of King Tros, whom Jupiter, having taken the form of an eagle, transported to heaven on his back, as poets fabulously tell . . . . I think, therefore, that I shall not have done amiss if the First is called by me Io, the Second Europa, the Third, on account of its majesty of light, Ganymede, the Fourth Callisto . . . . This fancy, and the particular names given, were suggested to me by Kepler, Imperial Astronomer, when we met at Ratisbon fair in October 1613. So if, as a jest, and in memory of our friendship then begun, I hail him as joint father of these four stars, again I shall not be doing wrong.
    "S/2002 J1"... How romantic, how evocative!
    --
    -- Language is a virus from outer space.
    1. Re:Stupid name... by sg_oneill · · Score: 2

      Hell yeah.. I was about to post that it should be named "Shayne" (after me).... But CowboyNeal.... What a damn funny way to preserver this little zone in history...

      As much as you meant it as a joke.. It's really a damn fine suggestion.

      "Cowboyneal" the 3k wide geek moon. Bet it's full of wookies.

      --
      Excuse the Unicode crap in my posts. That's an apostrophe, and slashdot is busted.
  7. Finally! by Lu+Xun · · Score: 3, Funny

    Does it have tiny volcanos that have to be cleaned every day with a chimney broom? Now we know where that little boy from the stars returns to at the end of every episode!

    --
    That's not a soda... it's a caffeine delivery device!
  8. Cool money making scheme by div_2n · · Score: 5, Funny

    I think space agencies should auction off on e-bay the right to name new celestial bodies. Why not? Everything else is for auction. Could be fun.

    "Class, this is a picture of YourMomNaked as it completes its orbit cycle."

  9. Is Cowboy Neal wide enough to count as a moon? by YellowSnow · · Score: 4, Funny

    Readers have discovered a new post on the linux desktop, bringing its known retinue of dupes to a whopping 40. The new post, designated S/2002 J1, is only 3 k long, and has a highly inclined and eccentric style. Slashdot.org has the story. Again!

  10. Moons. by mraymer · · Score: 3, Interesting
    Someone else mentioned it seemed a little small to be called a moon. I don't really think there's any size cut off with moons, or planets for that matter. How many of you really think, say, Pluto should really be called a planet? Its moon is roughly the same size as Pluto it self, IRRC. ;)

    That aside, I wonder when the folks working on Celestia will release an update to display the new moon in the space similator.

    --

    "To confine our attention to terrestrial matters would be to limit the human spirit." -Stephen Hawking

    1. Re:Moons. by lvdrproject · · Score: 3, Interesting

      Actually, yes, Charon is roughly the same size as Pluto. This, along with Charon's orbit, has led many (including myself) to consider Pluto and Charon as a dual-planet system (i.e. they are both planets, orbiting around each other). Meanwhile, there are some that insist that neither is a planet. Astronomy is a tricky business, it seems.

  11. Re:moon by pVoid · · Score: 2
    Well, it's not on the plane that rings are on...

    I'd consider it space junk. But then again, I guess it holds some value for some scientists.

  12. Just Another Captured Asteroid by mbone · · Score: 5, Informative

    Like all of the newly discovered moons, this little bit of rock is just another captured asteroid - its retrograde (backwards) orbit is a dead giveaway. Simulations show that most of the captured moons will eventually wander back to the asteroid belt - so this is the solar system equivalent of a one night stand.

    BTW, the rings of Jupiter are close to the planet - this new moon is not. It's so far away you couldn't see it with the naked eye if you were so unwise as to stand on the surface of Europa or Io and look for it.

    1. Re:Just Another Captured Asteroid by mtec · · Score: 2

      So Jupiter is just a ... slut?

      --
      Cake or Death? Cake Please!
    2. Re:Just Another Captured Asteroid by mbone · · Score: 2

      Ah, yes, very perceptive.

      Neptune's system has clearly been disturbed in the past - both of the major satellites have big inclinations and one has an eccentric orbit. Theories that have been introduced to explain this do include the capture of Triton, maybe at the time of losing an earlier satellite - maybe Pluto. I doubt we will know the answer in my lifetime :(

      I was, or course, referring to the normal run of satellites of the Gas Giants, which is large and small moons close in in flat, equatorial orbits, and a host of small moons further out, in widely scattered orbits. It's the latter that are almost certainly "recent" captures.

    3. Re:Just Another Captured Asteroid by TheOnlyCoolTim · · Score: 2

      Basically. That's why all the larger moons are named after chicks he got it on with.

      Tim

      --
      Omnia vestra castrorum habetur nobis.
  13. Could this be a recent moon? by sielwolf · · Score: 3, Interesting

    How possible is it that this moon was recently captured in Jupiter's gravity (say in the last few years)? Maybe this could explain it's eccentric orbit (ie that it hit tangentally enough that it wasn't sucked in while not so shallow as to bounce away)? Does such a thing happen or am I blowing smoke out of my ass?

    *checks*

    Hmmm, no smoke yet.

    --
    What is music when you despise all sound?
    1. Re:Could this be a recent moon? by faqBastard · · Score: 2

      Well, I guess not *every* captured satellite has to end up like Shoemaker/Levy back in 1994. (Or Galileo later on next year, for that matter.) :-)

      Also, please see the previous comment by mbone for more elaboration--

  14. Mmm. by twiztidlojik · · Score: 2, Interesting

    Just one question: when is an object considered a moon?

    I've tried the USGS, the IAU, and a general google search. This is going to annoy me to no end until I get an answer.

    --
    I will now redundantly add my name to the end of my post. You know, in case you forgot me or something.
    1. Re:Mmm. by mbone · · Score: 5, Informative

      Simple (more or less) - if it orbits another body (not a star), and is not man-made, it's a moon. Size is not really a consideration - if you can detect it, it's worth cataloging.

      I believe that Dactyl, the moon of the asteroid Ida, is only about 100 meters across.

      The exception occurs in planetary rings, where a moon has to be bigger than the ordinary rubble of the ring to be considered a moon.

    2. Re:Mmm. by KewlPC · · Score: 2

      Some people have classified a stone that most of the time orbits sun and only part of the time orbits the earth, a moon of the earth

      Cruithne (pronounced croo-een-ya) doesn't really count as being a moon of earth's. It has a highly inclined orbit, and it never even goes around the earth. It's affected by the earth's gravity, but not in the normal way: because of the earth, Cruithne is in a horseshoe-shaped orbit around the Sun (it takes 770 years to go all the way around the Sun, but makes a single horseshoe orbit in less time). Strangely enough, it is also because of earth's gravity that Cruithne never goes around the earth: the combination of the Sun's gravity and the earth's gravity pulls it towards us, then sends it back the other way before it can get too close.

  15. Re:I thought it only had 16 moons by lvdrproject · · Score: 3, Interesting
    It depends on what you call "moons". Personally i think the term "moon" is less specific than the term "satellite". Pretty much anything that has a permanent orbit around a planet is a satellite. I wouldn't really consider a bunch of large rocks (i.e. under a few kilometres) "moons", though. Essentially it's semantics, but you can't deny the fact that they are satellites.

    As for where the other satellites came from....

    The discovery of the last eleven of them is discussed here (39);

    the eleven before those are discussed here (28);

    the one before those is discussed here (17);

    ... and the first sixteen you obviously already knew about.

  16. Re:I claim this new planet in the name of Slashdot by hacksoncode · · Score: 2

    Given its size, maybe it should just be "Dot".

  17. Tell the DEA somebody is growing pot there... by corebreech · · Score: 2

    And they'll seize it through the forfeiture laws, i.e., they'll steal it.

    --
    Is this truly the only Earth I can live on?
  18. Well, it's not the size, by mtec · · Score: 2

    it's if you lose it.

    --
    Cake or Death? Cake Please!
  19. Satellites, Moons, Humans by MacAndrew · · Score: 2

    Seems to me that the headline "Jupiter Adds Another to Its Ranks" isn't quite right. How about "Humans Discover 40th Jovian Moon, Take Credit For Putting It There."

    Interestingly, a whole stack of these moons were discovered around 2000 when astronomers decided to search existing photographic plates for them, then went looking for more. I remembered Jupiter have about 12. Read about it here. (An intereting solar system site in general.)

    As for moon v. satellite, a moon is simply a natural satellite. Some purists say that only the Earth has a Moon (capitalized) whereas other planets such as Jupiter have natural satellites. As mentioned in the link above, "captured asteroid" is another candidate for these irregular-orbit chunks. Our Moon, meanwhile, is very unusual in the Solar System for its great size relative to its planet -- about 25% IIRC. There are bigger moons elsewhere, but the strength the gravitational Earth-Moon attraction has many dramatic effects. (I've also read that the Moon is more greatly attracted by the Sun than the Earth, thus it orbits the Sun. Please don't ask me to explain or defend, but it sounded plausible...)

    BTW -- someone suggested non-moons are distinguished by being mostly metal (e.g., Landsat) -- well, many asteroids are mostly free metal, too (Fe, Co, Pt, and so on). If you want to split hairs, most rock is made of metallic compounds (Si, Fe, etc.).

    1. Re:Satellites, Moons, Humans by geoswan · · Score: 2
      ... Our Moon, meanwhile, is very unusual in the Solar System for its great size relative to its planet -- about 25% IIRC...

      The moon's diameter is about 25% of the Earth's diameter, but it is the relative difference in diameter that counts for Gravity. The moon is a bit more than 1% of the Earth's mass -- partly because the moon is less dense than the Earth, but mainly because the volume goes up with the cube of the dimensions.

      Pluto and its satellite Charon are also relatively close in size.

      Earlier in this thread someone suggested rules, like the self-referential rule that planets had to be Pluto sized or larger. When I was a kid Pluto was described as being larger than Mercury. So even Pluto isn't Pluto sized.

  20. Question: What would the planets be named... by mtec · · Score: 2

    If Taco and the Slashdot editors named them?

    --
    Cake or Death? Cake Please!
  21. Re:Would be fun to live on jupiter.... by Simon+Field · · Score: 2


    The surface gravity on Jupiter can be calculated from Newton 's Law of Universal Gravitation:

    F = G * (mass of Jupiter) * (your mass) / (radius of Jupiter squared)

    The ratio of the force of gravity on Earth to that of Jupiter is thus:

    Mass of Jupiter / Radius of Jupiter squared

    Jupiter has a mass that is 318 times that of the Earth and a radius that is 11.2 times that of the Earth.

    The surface gravity would be 318/(11.2)(11.2) = 2.5 times the Earth's.

    Now I have pulled 3 G's before -- and I am thicker than a few centimeters, although some still call me a pile of goo.

    --

    Free book: Science Toys You Can Make

  22. Must be a slow news day :) by voodoo1man · · Score: 2, Funny

    Wow, another moon of Jupiter discovered! Who would have thought? Even my astronomy professor says the whole Jupiter-has-a-lot-of-moons thing isn't very interesting (but that may be because it gets more press than his research, or maybe because he has to compete with those guys for timeshares on the Mauna Kea observatory).

    --

    In the great CONS chain of life, you can either be the CAR or be in the CDR.

  23. Re:Would be fun to live on jupiter.... by Simon+Field · · Score: 2


    So your value is 2.3 instead of 2.5.

    Perhaps the difference is from using different values for the radius of a gas giant.

    --

    Free book: Science Toys You Can Make

  24. This just in . . . by Lagrange5 · · Score: 3, Funny

    Astronomers have discovered two new specks of Jovian dust, JM20022812174130 and JM20022812174130A, which are Jupiter's 84,519,786,014th and 84,519,786,015th moons, respectively.

    Scientists are now beginning the process of officially naming the two new worlds. This is expected to pass through several committees before signature in March 2007.

    With the discovery, Jupiter is now 3,845,108,491 moons ahead of closest rival Saturn in the race for biggest posse in the solar system.

    --
    "Folks just call him Buckethead." -- Les Claypool
  25. Moons orbital data chart by becktabs · · Score: 2, Informative

    Here is a link to an intersting chart with orbital data for all moons in the solar system, including S2002 J1.

    Planetary Satellite Mean Orbital Parameters

  26. Well no, there's no "cutoff" size by kfg · · Score: 3, Interesting

    The whole thing is rather subjective really. Like when does a boat become a ship?

    The answer in both cases is somewhat similar. A ship is a vessel large enough to carry a boat. Not very enlightening actually, if you insist on rigid taxonomy for every little object in existence. After all, a 22' sailboat can carry an 8' tender on deck, and yet remains merely a boat, not a ship.

    The basic standard for being a planet is large enough to have a moon. Uh huh. Cue the self referencial infinate loop here.

    Although Pluto meets, barely, this standard, quietly in the backrooms it isn't even really considered a planet these days. If we knew as much about it in the 30's it probably never would have been classified as a planet in the first place. "Planet" is also largely considered to only apply to those major bodies that were formed as such with the solar system. Circumstancial evidenced suggests that Pluto started "life" as a moon of Neptune that "got away," possibly knocked out of orbit by a comet.

    That would mean Pluto is a planet that's *also* a moom, although without being a planetary satellite. It's a weird dude, dude.

    The only rule for being considered a moon is being "big enough" to be so classified. Uh huh. Cue thumb up nose routine here.

    The rule of, ummmmmmmmm, thumb, is if you can walk around on it it's a moon. Unless it isn't rocky, we're prejudiced against ice balls. Or maybe if it's discovered on Tuesday. Who knows?

    Of course most of these small moons of the gas giants wouldn't even come close to meeting the formed naturally in the system test. They're pretty much space junk that's ended up stuck in the planet's gravitational field as they wandered by. Captured asteroids. Cue video game joke here.

    Of course if you could literally anthropomorphise a bit of space rock and ask it what it was ( which I don't recommend because they hate that) it would almost certainly say, "Yahwe, now bugger off." It is what it is, and that's all that it is.

    This urge to rigidly classify everything is a human failing. The rocks themselves couldn't care less.

    KFG

    1. Re:Well no, there's no "cutoff" size by glenebob · · Score: 2
      "This urge to rigidly classify everything is a human failing."
      Why do you classify it as a failing, and with such a sweeping generality no less? Now that you've classified it, have you failed in some way?

      Believe it or not, that's a serious question. Who can explain why classification is so often said to be a failing?

  27. Re:I have to ask by volsung · · Score: 2, Funny

    Well, you see, back in 1917...

  28. What's the cutoff? by Lord+Bitman · · Score: 2

    At what point is something no longer called a "moon" and just given the title "Debris"? 3km sure is small.

    --
    -- 'The' Lord and Master Bitman On High, Master Of All
  29. 3 km, Eh? Almost Able To Resolve... by reallocate · · Score: 2

    ...a large black obelisk orbiting Jupiter.

    --
    -- Slashdot: When Public Access TV Says "No"
  30. Re:Rubble,rubble by mbone · · Score: 2

    Yes, it turns out that narrow sharp rings typically indicate one or more small satellites nearby acting as "shepards."

    Saturn has at least five "Shepard Moons" - S15 bounds the outer edge of the A ring, S13 and S14 dance with the F ring, giving it a braided appearance, and S10 and S11 lie just outside the ring system.

    Jupiter also has a ring satellite, J9, as does Neptune, Galatea, and I suspect that Uranus has some undiscovered ones also.

    All of these satellites are small, and most if not all were discovered by the Voyager spacecraft.

    More fun ring images and facts can be found on the ringmaster web site.

  31. Why worry about ambiguities? by jesterzog · · Score: 2

    If it freely orbits a star, is IN THAT STAR'S PLANE OF THE ECLIPTIC, it's a planet (note: this knocks Pluto off the list).

    I disagree, mostly because I think that trying to put such labels on things is always going to end up in ambiguities. The reason we call these things planets at all is because ancient observers saw them wandering through the sky. The reason satellites are often called moons is that Moon was the proper noun previously used to name the Earth's most obvious natural satellite. When more satellites were found around Jupiter and other planets, people called them moons. (I think the moon thing is true, but I haven't confirmed it.)

    Furthermore, your definition is based on ruling out bodies that "weren't formed as part of the star's disc", but it hasn't even been established that stars (and planets) formed in such a way. What's so bad about ambiguities?

    Humans are naturally experienced and equipped to deal with ambiguities. It's one of the things people excel at that machines don't. Why does it need to be categorised? Computers normally need categorisation for calculations, but computers can do what they need to do just by seeing them as blobs orbiting other blobs. Arbitrary labels are irrelevant. That's my point of view, anyway.

  32. Re:moon by Cyno01 · · Score: 2

    All of the planets past the belt have rings except pluto, and maybe neptune, i cant remember. I know for a fact that Jupiter and Uranus have very faint rings, which imo is part of the reason why we keep discovering new moons.

    --
    "Sic Semper Tyrannosaurus Rex."
  33. Luna and Sol by Cyno01 · · Score: 2
    Technically, "Moon" is the proper name for Earth's major satellite.
    Technically, I think the proper name for Earths Moon is Luna, but has generally become known as The Moon. Just like The Sun. There are trillions of stars out there, and if you want to get picky and clasify only stars with planets orbiting them as suns, then there are still probably millions of suns out there, but ours is still The Sun, not Sol, as it should be IMO.
    --
    "Sic Semper Tyrannosaurus Rex."
  34. JUPITER HAS RINGS!!!! by Cyno01 · · Score: 2

    After reading all these posts saying that anything orbiting a planet should be considered a moon, i'd like to point out that there are Jovian rings. Should we count all the little chunks of rock and specks of dust as moons too? Aren't a lot of these moons we've found just bigger chunks of rock in the rings?

    --
    "Sic Semper Tyrannosaurus Rex."
  35. Re:moon by ceejayoz · · Score: 4, Informative

    Jupiter doesn't have rings, eh? NASA might disagree with you there...

  36. Re:Isnt that the stupidest way to look at it? by Lord+Bitman · · Score: 2

    I'm calling something small which is thousands of times my size. Isnt that the very oposite of putting humans first on the list? Where the fuck do you find anything remotely human-related in that? Have you taken a look at our solar system? Things are pretty fucking large out there. I wouldnt call a stray human being flung around a planet a moon, but my question is 'is there someone who might?' What is the cutoff? 3km, compared to any other body in the system, is REALLY FUCK'N SMALL.
    Humans are too small to even bother noting the existence of.

    --
    -- 'The' Lord and Master Bitman On High, Master Of All
  37. What would be ironic. by TheOnlyCoolTim · · Score: 2

    We are crashing the probe into Jupiter to avoid contaminating or destroying life on Europa. What if we end up destroying life on Jupiter, and Europa never had any life anyway?

    Bit of a cosmic "D'OH!"

    Tim

    --
    Omnia vestra castrorum habetur nobis.
  38. I thought jupiter had 5,345,420 moons! by Tuxinatorium · · Score: 2

    That is, if you count each particle in the rings larger than 1 cubic centimeter

    --
    Repeal the DMCA!
  39. Re:astrotrivia by MacAndrew · · Score: 2

    Yeah, Pluto is the "bastard planet," its origins unclear. It could be a former satellite of Neptune.

    Have you heard the suggestion that the Moon really orbits the Sun, and to a lesser extent interacts with Earth? The idea is that the Moon's size plus its slow speed around Earth relative to Earth's speed around the Sun (so there is no retrograde motion) result in the Moon always "falling" towards the Sun. I don't have the math and physics background to evaluate this myself, and was of course startled to read it. read this