Earth May Once Have Had Multiple Moons 186
fyc writes "A new study from NASA's Ames Research Center has suggested that the collision of Earth and a Mars-sized object that created the Moon may also have resulted in the creation of tiny moonlets on Earth's Lagrangian points. 'Once captured, the Trojan satellites likely remained in their orbits for up to 100 million years, Lissauer and co-author John Chambers of the Carnegie Institution of Washington say. Then, gravitational tugs from the planets would have triggered changes in the Earth's orbit, ultimately causing the moons to become unmoored and drift away or crash into the Moon or Earth.'" The longest-lasting of such Trojans could have persisted for a billion years. They would have been a few tens of kilometers in diameter and would have appeared in the sky like bright stars.
More proof of the Gospels (Score:5, Funny)
But this is scientific proof that the Gospels according to George Lucas are the truth.
Re:More proof of the Gospels (Score:5, Informative)
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How? They had help: http://orcas.vclart.net/vcl/Artists/Kkatman/Bad_Ewoks_-_Xorak.jpg [vclart.net]
I think the new alliance is in deep kimshi!
Seriously, THIS would make a kick-ass Star Wars sequel!
Re:More proof of the Gospels (Score:5, Funny)
But this is scientific proof that the Gospels according to George Lucas are the truth.
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Mars, Jupiter, etc. were known to have multiple moons long before Star Wars.
thats no moon....... (Score:2, Funny)
continue.
Perhaps the asteroid that did for the dinosaurs.. (Score:5, Interesting)
Re:Perhaps the asteroid that did for the dinosaurs (Score:5, Insightful)
Re:Perhaps the asteroid that did for the dinosaurs (Score:5, Insightful)
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Nothing to say that these "moonlets" weren't made of the same stuff of the KT boundary. I forget the name of the particular rare mineral/ore/whatever that defines the KT boundary, but is there a large amount of it on the moon? If there is, wouldn't it then stand to reason that these moonlets would have been made of similar materials? And if they were made of similar materials, would it not then be possible for one of them to have caused the impact event that created the KT boundary?
Of
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In a number of globally-scattered locations, there is a narrow peak of concentration of iridium (element, atomic number 77, a platinum group metal) which is approximately coincident with the Cretaceous-Tertiary boundary. However this does not DEFINE the position of the "K/T boundary" - that is done by fossil content, and more specifically by the lowest position of certain
Re:Perhaps the asteroid that did for the dinosaurs (Score:2)
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Would it be moving quickly enough to have the kinetic energy required to do the kind of damage that was done? Given that it was stationary, it wouldn't be hitting earth at more then terminal velocity, right?
The key question is "stationary with regard to what?".
In the case of the Lagrangian points, the answer is "stationary in regard to the Earth/Moon System", NOT "stationary in regard to a point on the Earth's surface".
(Also, "just terminal velocity" with regard to the distance of either a Lagrangian point or a geosynchronous orbit would still be nothing to sneeze at, and given the "tens of kilometers across", the force of impact would be far from trivial.)
Not far fetched. (Score:5, Interesting)
Re:Not far fetched. (Score:5, Informative)
Except that this object isn't sharing the Earth's obit at all. It's in a solar orbit which is similar to the Earth's. In order to call something a "moon" of the Earth it would need to be orbiting the Earth.
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Actually, it's a newspaper policy that there's only one obit per customer.
Re:Not far fetched. (Score:5, Interesting)
Earth has Cruithne sharing it's orbit, which in it's own way is a "second moon"
If it's not permanently orbiting within the Earth's Hill sphere [wikipedia.org], it's no moon.
On a side not, since these moons were originally at Lagrangian points, it makes me wonder whether or not some of them could evolve into having a horseshoe orbit with the Earth. Actually a mission to one of these asteroids when they get about 1.5 Gm from Earth would be interesting and pretty easy as they would be close to Earth and moving pretty slowly. I guess you could look them up closer to find out if they share material in common with the Moon or anything.
That's no moon (Score:5, Insightful)
The real headline seems to be:
Post-collision debris from Lunar creation might have persisted a little bit longer than originally thought in these crazy gravitational slots, but no evidence is available to back up this theory, and it sure would be neat-o."
Yay.
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Reading the abstract of the article actually led me to think the opposite: "The L4 and L5 positions are a little less stable than previously thought, so the non-existence of objects in those locations nowadays cannot be used to demostrate the lack of such objects in the past." IAN
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Re:That's no moon (Score:5, Funny)
"Post-collision debris from Lunar creation might have persisted a little bit longer than originally thought in these crazy gravitational slots at a distance of r \approx R \sqrt[3]{\frac{M_2}{3 M_1}} which could be described as being such that the orbital period, corresponding to a circular orbit with this distance as radius around M2 in the absence of M1, is that of M2 around M1, divided by \sqrt{3}\approx 1.73...
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Or even "At Earth-Luna L4 and L5". Most orbits are also too eliptical to be approximated as
Not exactly newsworthy ... (Score:3, Funny)
Meanwhile a new study by me has suggested that reading Slashdot stops time and may also make you hyper-intelligent. Slashdotters would have bigger brains that could be farmed in the future to feed entire villages. Villagers would crack open the skulls with sharp metal straws which would be used to drink the brains out. A strong light then placed in the skull cavity would then shine in the night like bright stars.
Re:Not exactly newsworthy ... (Score:5, Funny)
Moon may have been filled with cheese (Score:3, Funny)
Moonlets? (Score:5, Funny)
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The idea was rejected because of copyright claims from The Cow Level government.
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Any observers? (Score:3, Funny)
Appeared to whom?
Re:Any observers? (Score:5, Funny)
Xenu of course! (Score:2)
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Future time travellers (Score:2)
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Appeared to whom?
Nobody. One of the first things you learn in astronomy (observation, not education) is how to distinguish between a star and a planet or moon. It's easy: stars twinkle, big balls of rock or gas don't. Next time you're out at night, try to find Venus (it's the brightest object after the moon and sun), and compare it to any bright stars in the sky like Polaris. Venus will look very static, like it's just a dot of paint on the sky. Long bef
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I'll be here all week, try the broccoli.
Not an especially unique theory. (Score:3, Insightful)
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insightful?
lagrangian points require two bodies
what was the second body creating the points while the moon was being formed?
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These days they have scientific theories about the orbits of planets and nobody talks about planets flying around any more.
Moons? Nomeclature? (Score:4, Insightful)
I have no problem with the theory, but if objects 'tens of kilometers' across are moons, then Pluto is surely a planet.
And don't call me Shirley.
Mod Parent Clueless (Score:5, Informative)
Planets are the huge and few main satellites of the sun. It's a category defined entirely by scarcity. There are only 8. Not 8000. Pluto can't be a planet and the hundreds or thousands of larger objects not be, but the fact that there were thousands of similar objects wasn't discovered until after Pluto was added to the planet list. It's just an act of intellectual honesty to note that Pluto is only unique historically for being seen early. But now we know: It's not a major satellite sufficient to be in the planet category. You call this arbitrary, but it's as unarbitrary as anything could be.
What the hell does this have to do with how big a moon is? Any object orbiting a planet is automatically a satellite, any satellite that is naturally occurring is automatically a moon (by some definitions, anyway). Perhaps you should invest in a good dictionary. They are free on the internet.
Thank goodness we don't have to rely on your inane concepts of 'fairness' in celestial bodies for our language needs.
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While I agree that the original post was clueless, the current definition of planet isn't useful scientifically. In addition to being ill-defined, it doesn't extend naturally to other star systems in two critical ways. First, it can only be used in mature single star systems like the Solar System where no perturbation of planets is possible. Second, it requires considerable effort to prove the object is "clearing" its neighborhood, whatever that means. Try doing that for a star system so far away that you c
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At the very least, "clearing it's neighborhood" should have a more precise meaning, such as: Clearing a ring equivalent to X times it's own diameter of all objects Y% of it's own size or mass. Without some kind of clarification, any dust in a planet's orbital trail could be interpreted to mean the planet hasn't "cleared it's neighborhood".
Or perhaps they do have a more precise definition, and it's just not included in the press releases? If that's the case, they should include it-- the definition would so
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Perhaps we should only consider elements up to Iron as atoms, everything else after Iron is just too big to be an atom. It doesn't change the fact that they're still there, but the "a
Maybe you are right... (Score:2)
HOWEVER...all the theories suggest that an earth sized object will be EXTREMLY unlikley in the Kupier belt or farther out UNLESS it was a loose planet that the sun captured.
You say we will inevitably find an earth sized object...you may be right, but finding one or two won't change anything....when you find HUNDREDS we will chat.
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I must've missed the part where we found HUNDREDS of objects the size of Pluto. Seems to me we've only found two or three so far.
Oh, wait! My bad. Changing the definition of planets to exclude Earth would be fundamentally wrong on so many levels, wouldn't it? Which is why the current definition had to be tweaked so much to exclude Pluto without a
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A few more than that are known [wikipedia.org]. Theoretically there are probably many more such objects, and very unlikely for there to be earth-sized objects.
There are more than eight planets. Pluto is a plant. Xena (or whatever official name they've assigned it) is a planet. Get over it.
No, Pluto is just a large Kuiper belt object, a glorified asteroid. You are the one who must get over it.
O
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And yes, Kuiper belt objects that aren't comets and are bigger than 10m across and smaller than a planet are asteroids [wikipedia.org].
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Did you have a point, or was this the best you could do?
Re:Maybe you are right... (Score:5, Informative)
The official deffinition of a planet is:
The IAU therefore resolves that planets and other bodies in our Solar System, except satellites, be defined into three distinct categories in the following way:
(1) A "planet" is a celestial body that: (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.
(2) A "dwarf planet" is a celestial body that: (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape2, (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.
(3) All other objects3 except satellites orbiting the Sun shall be referred to collectively as "Small Solar System Bodies".
Footnotes:
1 The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
2 An IAU process will be established to assign borderline objects into either "dwarf planet" and other categories.
3 These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.
While a body of insufficient size will not "overcome rigids body forces" or have "cleared the neighbourhood around its orbit" the deffinition doesn't state that it must be at least 2000 km in diameter (which is arbitrary and was a running contender for the deffinition of planet). Infact you could have a very dense but small object (smaller than pluto) meet the deffinition of planet and a very defuse but large object (larger than the earth) NOT meet the deffinition. While size and mass are important, they are not what define a planet.
Since pluto hasn't cleared it's local neighborhood, it is not a planet. In addition, hundreds of pluto sized object HAVE been found in the oort cloud and Kupier Belt. However when a similar object was found orbiting inside Neuptune (Eris I beleive) it only accelerated the redeffinition of planet that was already underway.
This deffinition is actually pretty reasonable based on what types of objects dominate a solar system (excluding the sun) and how they are formed. If you look at the history of where this new deffinition came from you will find that the "devolved" scientists almost made an exception for Pluto but in the end decided to
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I'll bite. What is the definition of "neighborhood" in this context?
Is Cruithne in Earth's "neighborhood"?
If not, what is closer to Pluto than Cruithne that it hasn't cleared?
Besides Charon?
If Charon isn't excluded, does this mean that any binary planet is, by definition, NOT a planet?
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But based on what I have read, the concept of neighborhood is based off of how much influence the body in question has on everything else in the same (or very similar) orbits.
Therefore since Cruinthe is orbitally locked with the Earth, the Earth has "cleared" it's orbit of everything random. (Of course there are random asteroids, comets etc that cross the orbit but aren't considered part of the neighborhood).
As far as pluto goes, it's orbit is extremly messy. If you look
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And the fact that those Kuiper Belt objects in question are generally farther from Pluto (which is smaller than Earth) than, say, Earth is from Neptune doesn't mean much, eh? Face it, if Jupiter were that far out, it wouldn't have cleared that orbit either (note that Jupiter is closer to Pluto than most of the Kuiper Belt objects sharing Pluto's orbit)
We seem to've set up a definition that pretty much puts a maximum dist
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This definition while on the face of it seems arbitrary really is very precise and DOES describe a major difference between heavenly bodies.
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You'll have to explain that one. Mercury is less massive than Mars, but would definitely clear an orbit 12 terameters across, while Mars is only questionable?
So, why is Mars "questionable", when the only thing that should matter, within a given orbit, is the mass of the "planet" (or not-"planet"). I'd always thought Mars was the "we
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However you are also forgetting the definition of neighborhood (which I only found after my original post) which is the same average distance from the primary and an orbit that is not more than an order of magnitude difference in elliptical shape (it is beyond me to characterize this further, if you want more information go to peer-reviewed journa
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Nonsense! Mercury's greater density has little, if any, greater effect on its "neighborhood" further out than the radius of Mars (the planet, not its orbit). Sure, Mercury's atmosphere will be affected by its greater density, but something passing 250,000 Km away will only notice its smaller mass, not its higher density.
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Well, no.
Actually, our definition of "planet" makes them unlikely as you go farther out. A different definition doesn't have to have that limitation. For instance, if we stuck with "big enough that gravity pulls it into a quasi-spherical
Re:Maybe you are right... (Score:4, Insightful)
Actually, when it comes to terms like "planet", we've pretty much done just that. The original term "planeta" was from the Greek, and meant "wanderer". It was a term that referred to the celestial objects that "wandered" about the firmament, unlike the thousands of fixed stars that stayed in the same position. The list of planets included the sun and moon, but it didn't include the Earth, because from our viewpoint, the Earth doesn't wander about in the night sky.
Eventually people figured out that the Earth wasn't the center of everything, and made a revised heliocentric model. In that model, it was the sun that was stationary at the center, and the Earth became a planet that wandered about in an elliptical orbit. The moon got demoted to a different class at about the same time, because it appeared to orbit the Earth rather than the sun, putting it into a class with the four moons of Jupiter that people could see through telescopes. We went from Earth+planets+stars to sun+planets+moons+stars, and three bodies changed their classification.
So, yes, we did change the definition of "planet" back then to give us the answers we wanted. This was done because the prevailing definition of "planet" only worked for the Earth-centered model, and we'd decided to throw that model out. We didn't discard the term "planet"; we just gave it a new definition that fit the new model (and added "moon" as a classifier for a set that quickly picked up a lot of members).
In any case, there is a certain silliness to the seriousness of a debate over what is really a minor descriptive term that has little actual physical meaning. Thus, it has been pointed out that Titan is much more Earth-like than is Mercury, but Titan is called a moon rather than a planet. Earth's moon is more like Mercury than it is like Titan, including having an orbit about the sun that's nearly circular, leading some astronomers to propose calling the Earth/Luna system a "binary planet" rather than a planet and a moon. This isn't so much a serious suggestion, as it is pointing out the silliness of the argument and the irrelevancy of the terms in question.
Scientists do occasionally revise their definitions of technical terms to fit with the prevailing theories. Sometimes they make up new terms, of course. But sometimes it's easier to just tweak the definitions of the old terms.
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Apparentely so - the 63 Moons of Jupiter [wikipedia.org] include the 1 km in diameter 2003 J 9 [wikipedia.org].
I find it odd that people can't cope with there being hundreds of planets, and need some arbitrary distinction between "planet" and "natural satellite of the Sun", but 240 moons in the solar system is considered fine.
It's also strange that a body orbi
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I actually accept the arguments that Pluto isn't a planet. The problem is that defining a planet is a tough thing, and the oddity I noted above seems to be part of an odd compromise that shouldn't have been made.
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Mars is a planet because it is by a huge margin the biggest thing in that part of the solar system. The same can not be said of Pluto.
A "mmon" is simply any natural object capured in orbit around a planet.
Asstronomically Speaking (Score:4, Funny)
This "many moons" phenomenon was occasionally seen at my university quite some time in the past. The moons appeared as pale, bifurcated disks in the darkness around the president's residence, often after the end of final exams.
I'm not sure about this (Score:2)
Earth's 2nd Moon (Score:2)
Just because NASA can't find it, doesn't mean that it doesn't exist!
Explains Vaalbara & lunar maria (Score:2)
A good time was not had by all :)
Explains the variety of cheeses then (Score:3, Funny)
The swiss got to the other moons before NASA and mined them clean.
I stand by my theory.
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--
Miss A. Elk
Don't forget Earth's other moon - Cruithne (Score:4, Informative)
Time traveler tip #234 (Score:3, Funny)
From a trillion to one "moon" (Score:2)
I think what this article adds is detail about that period when there were only a few clumps.
I think logically we knew that if th
Re:OK, I'll bite.... (Score:5, Funny)
It amazes me that so many allegedly "educated" people have fallen so quickly and so hard for a fraudulent fabrication of such laughable proportions. The very idea that a gigantic ball of rock happens to orbit our planet, showing itself in neat, four-week cycles -- with the same side facing us all the time -- is ludicrous. Furthermore, it is an insult to common sense and a damnable affront to intellectual honesty and integrity. That people actually believe it is evidence that the liberals have wrested the last vestiges of control of our public school system from decent, God-fearing Americans (as if any further evidence was needed! Daddy's Roommate? God Almighty!)
Documentaries such as Enemy of the State have accurately portrayed the elaborate, byzantine network of surveillance satellites that the liberals have sent into space to spy on law-abiding Americans. Equipped with technology developed by Handgun Control, Inc., these satellites have the ability to detect firearms from hundreds of kilometers up. That's right, neighbors
Of course, this all works fine during the day, but what about at night? Even the liberals can't control the rotation of the Earth to prevent nightfall from setting in (only Joshua was able to ask for that particular favor!) That's where the "moon" comes in. Powered by nuclear reactors, the "moon" is nothing more than an enormous balloon, emitting trillions of candlepower of gun-revealing light. Piloted by key members of the liberal community, the "moon" is strategically moved across the country, pointing out those who dare to make use of their God-given rights at night!
Yes, I know this probably sounds paranoid and preposterous, but consider this. Despite what the revisionist historians tell you, there is no mention of the "moon" anywhere in literature or historical documents -- anywhere -- before 1950. That is when it was initially launched. When President Josef Kennedy, at the State of the Union address, proclaimed "We choose to go to the moon", he may as well have said "We choose to go to the weather balloon." The subsequent faking of a "moon" landing on national TV was the first step in a long history of the erosion of our constitutional rights by leftists in this country. No longer can we hide from our government when the sun goes down.
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So what you're trying to say is:
That's no moon [xkcd.com]!
To paraphrase GP... (Score:2)
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Mega-Dittos Rush! (Score:2)
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It does. Io's volcanos are powered by gravitational effects. Mostly in interaction with the other large Jovian moons, IIRC
It's all about the mass! (Score:5, Informative)
If the mass of the satellites starts to approach the mass of the parent then the system will become unstable. The Moon is by far the largest satellite as a percentage of mass anywhere in the solar system. The Pluto-Charon system beats the Earth and Moon but Pluto was downgraded from a planet. For the earth-moon system, the center of mass for the system is still inside the earth. The Pluto-Charon system the center of mass is roughly 1/3 of the way to Charon. The only reason it is stable is because it is so far away.
If the moon was significantly larger (or there was an additional moon of significant size) they system would become unstable and tend to lose satellites until it WAS stable.
Jupiter's moons are so much lighter that Jupiter has an iron gravitational grip on them. Short of a major external disruption (say getting hit by another moon) all of Jupiter's moons are staying put.
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Two points :
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Did you miss the memo on the latest archaeological findings? Man, you must have been living under a rock. Check out some of the news stories and peer reviewed journals on it-- utterly fascinating stuff. They think the Triceratops may even have discovered the Higgs Boson!
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The crux of the story is that a sun with its planets passed through our solar system. This sun did not have enough energy to burn so was a dwarf. The Sumerians called this sun Marduk(also known as Nibiru).
Now Earth was not yet one of the planets of our sun but there was one called Tiamet that resided in the orbit where the asteroid belt is now located.
Marduk did not hit Tiamet directly but
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he is saying that images of such activities shouldn't be illegal. And he is making a pretty logical argument.
Agreed - in fact, this law (which was covered recently on Slashdot, with most comments objecting to the plans) covers entirely staged acts or fictional images, i.e., someone play-acting.
I'm amused that RMS is seemingly most concerned about corpses (although he makes a good point about that bit of the law); the problem with this law is that it