Captured Comet Becomes Moon of Jupiter 108
An anonymous reader writes 'Jupiter's gravity captured a comet in the mid-20th century, holding it in orbit as a temporary moon for 12 years. The comet, named 147P/Kushida-Muramatsu, is the fifth body known to have been pulled by Jupiter from its orbit around the Sun. The discovery adds to our understanding of how Jupiter interferes with objects from the 'Hilda group,' which are asteroids and comets with orbits related to Jupiter's orbit.'
The comet's shape (Score:5, Funny)
The comet's shape was revealed to be rectilinear, with an aspect ratio comprising the squares of the first 3 non-zero positive primes.
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My God, it's full of stars.
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The squares of the first 3 positive integers, you mean.
1 is NOT a prime number.
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That was not an entirely settled matter when The Sentinel was written.
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Re:The comet's shape (Score:5, Informative)
From Wikipedia:
At least I came by it honestly.
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non-zero positive primes
Isn't that somewhat redundant?
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No, because "non-zero" can be negative too. Although I suppose the end result will be positive regardless...
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I'd say it's doubly redundant. Primes are, by definition, both nonzero and positive.
Nonzero and positive are only slightly redundant themselves, since mathematics will only occasionally deal with positive and negative zero. Computers may also consider zero to be a positive number, so "nonzero and positive" might not be redundant in computing.
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Prime number [wikipedia.org]:
Natural number [wikipedia.org]:
Every prime number is a natural number, and every natural nu
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So no, it's not redundant, given the conditions I assumed (I feel I have to say it explicitly this time
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Every prime number is a natural number, and every natural number is a positive/non-negative (depending on which definition you choose) integer. "Positive prime" is redundant.
The "positive" part is not the redundant part... it is the "nonzero" part that is. You have started with "every prime number is a natural number", which is a false premise... you can't rely on wikipedia for everything.
More precisely, that definition taken from wikipedia is closer to that for an irreducible, not a prime.
A nonzero element p in a ring is a prime if when p divides a product "ab", then p must divide one of the factors "a" or "b". A nonzero element p is irreducible if whenever you write p = st
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I call BS. Citation needed.
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For example, first paragraph, Chap 4, Stewart & Tall, "Algebraic Number Theory", 2nd ed., 1987, Chapman & Hall: (I write \pm for "plus or minus")
In Z we can factorize into prime numbers and obtain a factorization which is unique except for the order of factors and the presence of units \pm 1. Such a notion of unique factorization does not carry over to all rings of integers, but it does hold in some cases. As we shall see this caused a great deal of confusion in the history of the subject. The nub of the problem turned out to be the definition of a prime. In Z a prime number has two basic properties:
(1) m | p implies m = \pm p or \pm 1,
(2) p | mn implies p | m or p | n.
Either of these will do as the definition of a prime number in Z, and we usually take the former. In an arbitrary domain, it turns out that property (2) is what is required for uniqueness of factorization and in general (2) does not follow from (1). Property (1) is simply the definition of an irreducible element in Z. We will reserve the term prime for an element which satisfies (2) and is neither zero nor a unit. A prime is always irreducible, but not vice versa.
It is interesting to note the bit that says "we usually take the former". On this point, I stand corrected. When authors are restricting their attention to cases where all irreducibles are primes (for instance, when only considering Z like in the original discussion here on /.), they do seem to prefer property (1) as their definition. (e.g. Birkhoff and
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I actually probably shouldn't have bothered; right after posting that I googled it and realised that there's actually a fair degree of controversy on the subject.
I still maintain that negatives should be excluded from consideration in the definition for primes. If you don't, you have to change too much to make things work for negatives.
E.g. what is the prime factorization of -60... which factor is negative? Are we going to allow -1 to be a prime, so that we don't need other negative prime factors? Is -3 a p
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Yep, I see where you're coming from. I'd like to let you know though that with regards negatives causing confusion, I guess that would depend on the context, for certainly from the algebraic point of view, excluding them is what would actually be problematic! That's why in mathematics we include them. But one thing's for certain: if we're only discussing natural numbers in the first place, there can be no confusion at all.
With regards some of your questions:
- What is the prime factorization of -60? (-2)(
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Yes, but that's not really at question here. Allowing negative numbers opens a whole new set of possibilities.
7 divides evenly by 1, -1, 7, or -7. Is it still prime?
What about -7?
What are the prime factors of -12?
Is -3 a prime factor of 12?
It's easier just to limit primes (and the numbers we're dividing them by) to positive integers.
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At some level, primes are defined to be positive and non zero (or at least, that is the way I have understood things, but I'm no mathematician, so the 'real' definition may be a good deal more complicated than the simplified one us normal people use).
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The comet's shape was revealed to be rectilinear
Though some thought it a doorway with stars in here
with an aspect ratio comprising the squares
of the first 3 non-zero positive primes.
Burma shave
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The comet's shape was revealed to be rectilinear, with an aspect ratio comprising the squares of the first 3 non-zero positive primes.
I thought only Uranus was rectalinear.
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No, you're thinking of rectumlinear.
But... (Score:5, Funny)
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Well, it was for 12 years
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Good catch Jupiter (Score:5, Insightful)
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Re:Good catch Jupiter (Score:5, Informative)
Yes, it did. A planet like Jupiter may actually have been essential for complex life to develop on Earth.
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What an intelligent design to put it there, to dispose of all the garbage.
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And if it wasn't there, we may not be here to wonder why.
Re:Good catch Jupiter (Score:5, Funny)
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Yes, it did. A planet like Jupiter may actually have been essential for complex life to develop on Earth.
Maybe. However in addition to capturing bodies that could have threatened earth, Jupiter also attracts objects from the Oort Cloud etc. that would not have been any threat to Earth otherwise. The jury is still out on whether Jupiter is actually a net positive.
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What I want to know is... was a flickering bat logo projected onto the clouds of Jupiter right before this rogue comet was incarcerated?
Deep Thought (Score:5, Funny)
"Whether they ever find life there or not, I think Jupiter should be considered an enemy planet." - Jack Handey
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Why yes, I am an MS shill - I earned US$10 for this post alone !
Do they have an affiliate program? I am prepared to prostitute myself. Posting on /. is getting laid for nerds
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Re:This should be NASA's focus (Score:5, Funny)
Yeah, and it's been thrown around the table a few times, but we still haven't figured out what sort of payment Jupiter will accept (or how to get it there). Hiring out gas giants for protection turns out to be less easy than you'd expect.
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Maybe Jupiter is Mafia. It protects us, but expects some kind of payment. Maybe free planet pr0n? I hear Uranus has a nice...
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Maybe Jupiter is Mafia. It protects us, but expects some kind of payment. Maybe free planet pr0n? I hear Uranus has a nice...
Shhh. It's a conspiracy. Remember how Pluto got reclassified as a "dwarf planet"? They did that because Jupiter's got a "little planet" fetish.
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Asteroidophile, eh?
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They already did: They created Jupiter!
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Re:This should be NASA's focus (Score:5, Insightful)
With all due respect, I disagree. Yes, some resources should be directed at that problem. But there is so much more that can and should be done by NASA. The Hubble, Chandra, and Spitzer telescopes are a good example.
But what is the point in surviving if all we are doing is treading water? Sure we could spend billions on monitoring near space for potentially dangerous objects, but IMO we're better off spending those billions on things that can advance technology.
And in the (very) long run, our currently feeble attempts at space travel may lead to the best defense against catastrophic collisions -- another colonized planet.
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Re:This should be NASA's focus (Score:5, Insightful)
Sorry, but how is colonizing another planet going to prevent a catastrophic collision?
Imagine when all of what would become the human race lived in one valley in Africa. One particularly harsh winter or dry summer could wipe out the whole species, right? If that happened today it might still be a catastrophe but humanity would go on. If we had self-sufficient colonies on other planets, an asteroid could destroy the earth without killing off humanity.
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It wouldn't prevent the collision, but it would prevent the catastrophe of eliminating all human life.
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What it will do is lessen the relative damage caused by such an impact.
Instead of wiping out all of humanity, and drastically change the ecosystem humans live in, it will only wipe out part of humanity, and some of the ecosystems we live in.
You know that old adage about putting all your eggs in one basket (don't do it!) -- we currently have all our eggs in one basket, and it would be nice if we could change that situation.
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Sorry, but how is colonizing another planet going to prevent a catastrophic collision?
No need to be sorry, it's a good question. See, the aliens only have the resources to throw biosphere-destroying meteors at one planet, and if we spread to more than one they will save their resources for defense against our inevitable invasion and conquering of their own planets.
It makes perfect sense once you have all the data. See http://traipse.com/upgrade/index.html [traipse.com] for another idea about averting a catastrophic col
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We are the first and only known organism that has the ability to improve the state of it's species. We have the ability to make ourselves great and prosper and you propose we do nothing more than simply survive. Take about underachievement.
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Nice straw man yourself.
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Who cares about the species? I want to detect the coming apocalypse and move before it happens. Frying all human life on planet earth will be game over for me, and I find very little comfort in the knowledge that humanity will survive elsewhere in the galaxy.
Yes, we both just watched Numbers, didn't we?
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I'd just like to go on records as saying Numbers is painful to watch from a mathematical point of view. It most definitely does not earn you any geek points.
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I meant Knowing. I haven't seen Numbers.
I can't believe I didn't remember that.
SPOILER (to explain why the movie is relevant to my post, if you haven't seen it and don't mind reading a complete spoiler):
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NASA should be spending most - if not all - of its budget preparing to avert a comet/asteroid from hitting earth.
No! We should be concentrating on moving our entire solar system away from the galactic core at just under the speed of light. After we clear out all asteroids and comets. Signed, Hindmost
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Everything else is moot if we let that happen.
mmkay, bit of a stretch as an example-- but it seems extremely shortsighted for the National Aeronautics and Space Administration to be solely focused on potentially dangerous bodies. We wouldn't have the capability of deflecting asteroids and comets if it wasn't for the technologies we've developed for exploration.
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NASAs goals and objectives are not solely to protect earth from dangerous rocks. It is a research and exploration agency. I can see that if you're terrified of dangerous space rocks, you'd want to see that mission changed. I simply think it's a bad idea to redirect all of your resources to fend off one threat which has a minuscule year to year statistical likelihood. Sure, don't ignore the threat, but don't give up on all the other exploration
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NASA should be spending most - if not all - of its budget preparing to avert a comet/asteroid from hitting earth.
Everything else is moot if we let that happen.
Unfortunately Congress is more concerned with steroids in baseball.
Sometimes I think we deserve to become extinct.
If we just gave enough steroids to the baseball players, they could probably hit any threatening meteors, asteroids, or comets out of the solar system, thereby solving both problems.
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That would be "Giovian" not Jupiterian.
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"Giovian" is the Italian part of the Jovian landscape. It is AKA the Red Spot.
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"in the mid-20th century" (Score:4, Funny)
Slashdot
History for nerds. Stuff that mattered.
I'll bet if I go back 50 years, I'll find a dupe in the archive.
Old News (Score:2)
'Jupiter's gravity captured a comet in the mid-20th century
Old news?
Avenge the Mammals! (Score:2)
The dinosaurs saved it there for eventual revenge on the mammals. It's like a snowball in the freezer so that you can pound your enemy in the summer, when they least expect it.
Wait a second... article may be overstating case (Score:3, Interesting)
The article says that the comet had an orbit around Jupiter of 12 years. Well Jupiter has an orbital period around the sun of almost exactly 12 years also. Does this mean that the comet was in orbit around Jupiter or that it was merely in an orbit that was very similar to Jupiter's (in relation to the sun).
I believe that there is a NEO that basically does the same thing around earth. It travels in an orbit around the sun just slightly different from the earth so that sometimes it is in front of the earth on it's path and sometimes it is behind. From our perspective it makes a complex lissajous (spelling?) track. But I seem to remember it is definitely NOT "orbiting" the earth.
The article doesn't specifically state whether or not the comet is gravitationally bound to Jupiter which I guess is the definition of "orbiting" (I'm not a professional astronomer). Even if it was orbiting Jupiter, with a period of 12 years it was very loosely bound. In any case, how was it brought into Jupiter's proximity? How did it get ejected? Where is it now?
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RTFA!
"between 1949 and 1961 two full revolutions around Jupiter were completed" (by the comet in question, around Jupiter)
Two revolutions is not much. It's an orbit, but not a steady orbit. Shoemaker-Levy 9 did 12 orbits in 50 years, a little bit more stable, but alas, it crashed into the planet.
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Does this mean that the comet was in orbit around Jupiter or that it was merely in an orbit that was very similar to Jupiter's (in relation to the sun).
The astronomer in the article said that the comet was in orbit around Jupiter -- ergo moon, not simply an object in a similar orbit around the sun.
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Jupiter has much less mass than the sun such that it's possible to have the same orbital period as Jupiter has around the sun, yet still be relatively close to Jupiter. A 12-year orbit around a small object is usually closer to the parent than a 12-year orbit around a large object.
However, at that far out, the comet risks being affected by other planets and bodies, such as Saturn. It's roughly comparable to sticking your head too far out of the car window: you risk getting womped about another car.
The Hilda Group? (Score:2)
I never really understood the whole "Hot Ice" thing (former jewel thief, maybe?) but Hilda was awesome. Pity she had to buy it early on in the series so Gene could be the star.
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Either a gravitational slingshot effect from Jupiter's moons, or they're defining "orbit" pretty loosely.
and i exclaimed, (Score:2)
by jove, another moon!
And another "jupiter shield" hit. (Score:2)
I thought the "Jupiter Shield" myth was pretty much busted.
oh great... (Score:1)