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Author Topic: Why is the Sun destined to die?  (Read 3073 times)

Offline Judi Warner

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Why is the Sun destined to die?
« on: 18/10/2009 20:30:03 »
Judi Warner asked the Naked Scientists:
   If energy cannot be destroyed, why will the Sun one day die?
What do you think?


 

Offline neilep

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Why is the Sun destined to die?
« Reply #1 on: 18/10/2009 21:33:12 »
Because, like a car engine, it'll eventually run out of fuel and there's no gas stations in space !..the sun is effectively just a big ball of gas. It is burning up. It's just it's fantastic mass/gravity that stops it from blowing apart. One day, all the gas will be gone.
 

Offline Geezer

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Why is the Sun destined to die?
« Reply #2 on: 18/10/2009 23:57:30 »
One day, all the gas will be gone.
Does that mean I'll be able to give up the charcoal biscuits?
 

Offline RD

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Why is the Sun destined to die?
« Reply #3 on: 19/10/2009 03:41:13 »
the sun is effectively just a big ball of gas. It is burning up.

Strictly speaking the nuclear fusion in the sun isn't the same as "burning".

(BTW Geezer, blame the dog).
« Last Edit: 19/10/2009 03:42:53 by RD »
 

Offline syhprum

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Why is the Sun destined to die?
« Reply #4 on: 19/10/2009 11:03:40 »
Of course the first product of the 'burning' is Helium quite innocuous.
 

Offline Geezer

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Why is the Sun destined to die?
« Reply #5 on: 20/10/2009 04:50:08 »
This thread seems to have "burned out", but it reminded me of the two old geezers who were in adjacent beds in a hospital somewhere in the South of England:

Geezer1: "Did you come 'ere to die?"

Geezer2: "No. I come 'ere yesterdie."
 

Offline Nizzle

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Why is the Sun destined to die?
« Reply #6 on: 20/10/2009 14:46:50 »
If you said 'two suns from South England' it'd be more on-topic ;)
 

Offline Soul Surfer

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Why is the Sun destined to die?
« Reply #7 on: 20/10/2009 23:12:25 »
To return to and hopefully answer the original question.  Judi,  Energy is not destroyed merely changed.  We can see that because the sun is shining and giving out light (and lots of other types of energy).  this is spreading out throughout the whole universe and warming it up a bit.

The sun can do this because as it condensed under the effect of its self gravitation out of cold gas the rise in pressure gradually causes it to warm up and eventually become hot enough to radiate.  inside it is much hotter. At the very high temperature inside of the sun the nuclei of atoms of hydrogen (its main constituent)can fuse to become the nuclei of atoms of helium and because these nuclei are very tightly bound together this can release a lot of energy which eventually comes out of the surface of the sun as light heat and a stream of neutrinos.

This source of energy will eventually run out when a significant proportion of the hydrogen has been converted into helium. The inside of the sun will continue it's collapse under the effects of its gravity and get even hotter. The result of this is that the sun will slowly expand but become less dense to become a red giant and eventually will blow away quite a lot of its mass to become a white dwarf star which is essentially the very hot but "dead" core of a modestly sized star like the sun.  This will over many many billions of years (much longer than the current age of our universe)slowly cool down and fade out.
 

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Why is the Sun destined to die?
« Reply #7 on: 20/10/2009 23:12:25 »

 

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