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Proportions is everything

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Sat, 2010-10-09 15:57

Quincey Forder Quincey Forder's picture

Proportions is everything

Everybody thinks that if you hide in the Asteroids Belt... ...And seeing that picture bellow, you're believe it too! [img]http://i.dailymail.co.uk/i/pix/2010/04/29/article-1269693-095796A6000005... I wasn't expecting the Trojans and Greeks to be so wide and numerous, though. There is a question that I have, since rereading Carmen McCallum's eighth volume. In the solar system, is there a spot called Void of Kirkwood ? I.E. is it real or creation of Fred Duval's, the writer of the comics

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Sat, 2010-10-09 17:29

Rhyx

Re: Proportions is everything

And here I was thinking this thread was about Lil Kim's bust size... The word you are looking for in English is the Kirkwood Gap: http://en.wikipedia.org/wiki/Kirkwood_gap

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[img]http://boxall.no-ip.org/img/A_Rep.jpg[/img] 2 [img]http://boxall.no-ip.org/img/R_Rep.jpg[/img] 7 [img]http://boxall.no-ip.org/img/C_Rep.jpg[/img] 2
[img]http://i.imgur.com/qtBZ9.jpg[/img]
[img]http://i.imgur.com/AT25J.jpg[/img]

Sat, 2010-10-09 19:58

puke

Re: Proportions is everything

this is a pretty cool video of the discovery of asteroids between 1980 and 2010. http://www.youtube.com/watch?v=zdXxl0h54AM there is really a mind-boggling lot of them, i suspect that many of them are rediscoveries of the same object where it didnt happen to follow the same course we guessed it would, or where someones measurements were off. the mass of the entire belt is only estimated to be 4% of that of the moon, and 1/3 of that is supposed to be taken up by Ceres (doubtless a hab in EP time).

Sun, 2010-10-10 02:18

Arenamontanus Arenamontanus's picture

Re: Proportions is everything

The Kirkwood gaps are there because of resonances with Jupiter (and other planets): asteroids inside them will be gently pulled in a regular way so that they change orbits. However, the thing that matters is the period of the asteroid, not it's exact location - hence the lack of nice bands. The divisions of Saturn's rings are due to the same effect (with Titan causing the Cassini Division for example) but here everything orbits nearly circularly. "Neighbours" in the asteroid belt are often more than a tenth of an AU apart. And they shift over time, changing trade. Right now Extropia and Locus might be close, but in a year's time Extropia is going to be near New Carrara and Greenaway instead.

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Sun, 2010-10-10 15:17

OneTrikPony OneTrikPony's picture

Re: Proportions is everything

Arenamontanus wrote:
Right now Extropia and Locus might be close, but in a year's time Extropia is going to be near New Carrara and Greenaway instead.

"Close" is kind of a realative term, as Locus is an L5 jovan trojan and shares jupiter's 12 year orbital period. What are New Carrara and Greenaway? I cant find any reference to them in the core books or on google?

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Mea Culpa: My mode of speech can make others feel uninvited to argue or participate. This is the EXACT opposite of what I intend when I post.

Mon, 2010-10-11 02:53

Arenamontanus Arenamontanus's picture

Re: Proportions is everything

Oops, I was thinking of some main belt asteroid rather than a Trojan. Not that the difference is enormous.

OneTrikPony wrote:
What are New Carrara and Greenaway? I cant find any reference to them in the core books or on google?

Oh, I just made them up.

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Mon, 2010-10-11 04:54

OneTrikPony OneTrikPony's picture

Re: Proportions is everything

LOL considering the source I just assumed. Hey, you'll be able to answer this; the reason that the Jovan L4,5 Trojans are spread over such a wide area is due to the eccentricity of Jupiter's orbit right? I'm thinking that as jupiter moves through periapsis and... (the other one that's not periapsis) it moves the focus of the lagrange points which means objects captured by the Lagrange want to orbit that focus and that's what makes the L4,5 orbits kidney shaped. So does that mean that objects obiting those points have the same orbital period (around the lagrange) as the smaller body? It feels like all three bodies ought to have some type of resonance for the system to work but I can't imagine the jovan trojans makeing a full circuit every 12 years. If there's one thing I'm learning (slowly) its that orbital mechanics is not a chaotic system but masses of trojan objects seem pretty chaotic to me.

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Mea Culpa: My mode of speech can make others feel uninvited to argue or participate. This is the EXACT opposite of what I intend when I post.

Mon, 2010-10-11 07:49

Arenamontanus Arenamontanus's picture

Re: Proportions is everything

OneTrikPony wrote:
Hey, you'll be able to answer this; the reason that the Jovan L4,5 Trojans are spread over such a wide area is due to the eccentricity of Jupiter's orbit right?

Nah, it is just because they are in loose orbits. The eccentricity is 0.0489, not much at all. What matters is that they have periods very close to Jupiter's. Then they (as seen from a camera rotating above the solar system, holding Jupiter in the same spot) orbit around the lagrange points. If you look by a fixed camera instead they have mildly eccentric orbits around the sun; it is the eccentricity of the trojans that make them move in and out, ahead and behind the lagrange points. http://www.youtube.com/watch?v=5bYDiUe3168 http://www.astro.uwo.ca/~wiegert/etrojans/etrojans.html

Quote:
If there's one thing I'm learning (slowly) its that orbital mechanics is not a chaotic system but masses of trojan objects seem pretty chaotic to me.

There is chaos in the mathematical sense in orbital mechanics, but not much in the inner system - all the really chaotic stuff has by now crashed into something or flown off. But there is plenty of randomness: where trojans are and how large they are, that is merely a "historical" accident due to what collided where. If you want a really weird orbit, check out Cruithne. http://www.astro.uwo.ca/~wiegert/3753/3753.html Or the quasi-satellites. http://www.astro.uwo.ca/~wiegert/quasi/quasi.html Nothing chaotic, just the right resonance.

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Wed, 2010-10-13 12:27

root

Re: Proportions is everything

root@Proportion is everything [hr] Have I mentioned that I dearly love this community? If you are interested in proportions, see if you can find an illustrative picture that includes the Oort belt out to the heliopause (I usually think of the heliopause as the border of a solar system because it creates enough interference to act as a communication filter between any sources inside and outside.). The Oort belt dwarfs the rest of the system by a breathtaking margin.

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Wed, 2010-10-13 13:29

#10

OneTrikPony OneTrikPony's picture

Re: Proportions is everything

Yet again, my mind is blown. At times like these I feel it's appropriate to quote the immortal word of Keanu Reeves; "Whoa." :D thanks Arenamontanus.

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Mea Culpa: My mode of speech can make others feel uninvited to argue or participate. This is the EXACT opposite of what I intend when I post.