where is the symmetry in planets?

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Offline JnA

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where is the symmetry in planets?
« on: 31/10/2010 08:02:17 »

I have been doing some reading about the formation of the solar system and I have a, probably rookie, question..

why didn't the planets form in size in ascending (or descending) order? a shockwave is quite formatic I would think..


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Offline Bored chemist

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Offline Soul Surfer

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where is the symmetry in planets?
« Reply #2 on: 31/10/2010 11:26:23 »
There are two effects in governing the amount of material available for planetary formation from a discoidal cloud  of material surrounding the forming star.  The amount of volume that can be "swept" by the gravity of the forming planet and the amount of material in that volume  given a particular mass of growing planet the volume available is greater the further the planet is from the star. however the density of the cloud is probably getting less as you move away from the star.  So it seems logical that close in planets are likely to be smaller and further out ones bit larger up to a point and then eventually tail off as the material becomes sparse.

Other effects include the local temperature and the ability of the forming planet to hold on to light gasses in the initial flare of the star formation.  A star like the sun is very much brighter for a short period very early in its life before it settles down to a stable main sequence position and the Earth probably got a good frying which stripped all of its earlier atmosphere.  Jupiter and planets beyond probably avoided this fate.  If it hadn't the earth could have been the size of Uranus or Neptune if it had held on to all its gases when you consider the ratio of dense material to gases in the cloud.

It is also interesting to note that the formation of planets is an essential part of star formation because the planets trap the excess angular momentum in the cloud and allow the cloud to form a small object like a star without excessive rotation speeds disrupting it.
« Last Edit: 01/11/2010 08:53:56 by Soul Surfer »
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Offline imatfaal

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where is the symmetry in planets?
« Reply #3 on: 31/10/2010 14:53:01 »
Question is: what did Bored Chemist mean?  Or is there a spoofer in our ranks?
Thereís no sense in being precise when you donít even know what youíre talking about.  John Von Neumann

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Offline RD

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where is the symmetry in planets?
« Reply #4 on: 31/10/2010 15:26:24 »
why didn't the planets form in size in ascending (or descending) order?

They are in order of density ... http://en.wikipedia.org/wiki/Terrestrial_planet#Density_trends
« Last Edit: 31/10/2010 15:39:40 by RD »

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Offline maffsolo

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where is the symmetry in planets?
« Reply #5 on: 31/10/2010 17:47:41 »
Question is: what did Bored Chemist mean?  Or is there a spoofer in our ranks?


Along with material, position of the mass, matter accretion, and from the oven to the freezer, these masses in our solar system is also have to have been cooking, at different temperatures, over billions of years. This later factor is observed also.

Poor Pluto has been dismissed as a planet.
It also can be included here if you wish...

why didn't the planets form in size in ascending (or descending) order?

They are in order of density ... http://en.wikipedia.org/wiki/Terrestrial_planet#Density_trends


Nasa being the source, this chart is sorted in the order of density.

[attachment=13302]


The density order does not match the order of distance from the Sun, Why?

http://www.smartconversion.com/otherInfo/Density_of_planets_and_the_Sun.aspx

Nasa  trumphs Wakiypedia, wikipedia scrambled my eggs to many times to depend on, as a source, to be the do all end all.
« Last Edit: 31/10/2010 18:16:09 by maffsolo »

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Offline JnA

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where is the symmetry in planets?
« Reply #6 on: 01/11/2010 01:58:37 »

So we have randomness out of pattern.

And, on further investigation I find out that the planets aren't necessarily in their original orbit when they were formed..  where were you people on planet migration?

:)

Thanks all.

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Offline Bored chemist

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where is the symmetry in planets?
« Reply #7 on: 01/11/2010 07:08:02 »
I wondered what the word "formatic" meant.
All the references I could find led to that site or one like it.
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Offline imatfaal

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where is the symmetry in planets?
« Reply #8 on: 01/11/2010 10:51:52 »
Aha - that explains matters; perhaps the reason I am not a professional scientist is that I had to read the sentence more than a couple of times before I noticed the word.
Thereís no sense in being precise when you donít even know what youíre talking about.  John Von Neumann

At the surface, we may appear as intellects, helpful people, friendly staff or protectors of the interwebs. Deep down inside, we're all trolls. CaptainPanic @ sf.n