What keeps planets from being crushed by gravity like stars?

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Stephanie

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Stephanie asked the Naked Scientists:
   
As I understand it the nuclear fusion of stars stops gravity from compressing them until they cannot be compressed anymore because of the force of the neutrons repelling each other; when stars run out of fusible materials they are compressed to this point.

So what keeps the planets from being compressed by gravity as the stars are when they run out of fusible materials?

What do you think?

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Offline lightarrow

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What keeps planets from being crushed by gravity like stars?
« Reply #1 on: 06/09/2009 11:36:24 »
Stephanie asked the Naked Scientists:
   
As I understand it the nuclear fusion of stars stops gravity from compressing them until they cannot be compressed anymore because of the force of the neutrons repelling each other; when stars run out of fusible materials they are compressed to this point.

So what keeps the planets from being compressed by gravity as the stars are when they run out of fusible materials?

What do you think?
A planet's mass is much lower than a star's mass.

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lyner

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What keeps planets from being crushed by gravity like stars?
« Reply #2 on: 06/09/2009 12:51:45 »
. . . . .  so the internal gravitational attraction is not enough to cause crushing. The atoms are strong enough to withstand the force in planets.

(added for clarity, lightarrow - OK?)

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Offline lightarrow

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What keeps planets from being crushed by gravity like stars?
« Reply #3 on: 06/09/2009 18:27:28 »
. . . . .  so the internal gravitational attraction is not enough to cause crushing. The atoms are strong enough to withstand the force in planets.

(added for clarity, lightarrow - OK?)
Ok. I was lazy, didn't want to add anything else  [:)]

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Offline wanhafizi

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What keeps planets from being crushed by gravity like stars?
« Reply #4 on: 07/09/2009 16:15:36 »
Quote
So what keeps the planets from being compressed by gravity as the stars are when they run out of fusible materials?

But, for some stars, humangeous super nova explosion compress the centre of the star...

...i think...

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Offline LeeE

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What keeps planets from being crushed by gravity like stars?
« Reply #5 on: 07/09/2009 22:28:54 »
The radiation implosion of a super-nova that results in a black hole isn't really too different from the radiation implosion that is used to start the fusion process in fission-fusion and fission-fusion-fission bombs.

I believe that much of the initial mass of a pre-super-nova star is blown away by the explosion and the mass of the resulting neutron star or BH is far less than the star's original mass i.e. although our sun could form a BH if it were 1.4 times larger, the resulting BH would have less than 1.4 solar masses.

Not sure about this though, off hand.
...And its claws are as big as cups, and for some reason it's got a tremendous fear of stamps! And Mrs Doyle was telling me it's got magnets on its tail, so if you're made out of metal it can attach itself to you! And instead of a mouth it's got four arses!

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Offline thedoc

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