# When the sun burns out
**URL:** https://boards.straightdope.com/t/when-the-sun-burns-out/233681
**Category:** Factual Questions
**Created:** [March 11, 2004, 12:47pm UTC](https://boards.straightdope.com/t/when-the-sun-burns-out/233681 "2004-03-11T12:47:00Z")
**Posts on this page:** 9
**Page:** 1
### Author:  [@welloso](https://boards.straightdope.com/u/welloso)
#### Post date: [March 11, 2004, 12:47pm UTC](https://boards.straightdope.com/t/when-the-sun-burns-out/233681/1 "2004-03-11T12:47:00Z")
I know it might not happen today or tomorrow , but it is going to happen one day they say , the sun will burn itself out . Has there been any research into what will happen when that day arrives , or is it because the time is so far off we may be able to deal with it then due to advances in technology in the next few billions of years , no one has botherd to look into it ? That is if we havent all killed each other by then . What would become of us if the sun went out tomorrow?
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### Author:  [@Malacandra](https://boards.straightdope.com/u/Malacandra)
#### Post date: [March 11, 2004, 1:13pm UTC](https://boards.straightdope.com/t/when-the-sun-burns-out/233681/2 "2004-03-11T13:13:23Z")
If the Sun went out tomorrow we’d be screwed, pure and simple. The entire ecosystem would collapse, and in a short-ish space of time the atmosphere would freeze out. OTOH there’s no immediate danger. According to our best understanding of how stars work, the Sun in its present condition has billions of years to go. It’s extremely unlikely that any descendants of humanity that are about the place by then will resemble us any more than we resemble _e coli_ and if we haven’t rendered ourselves extinct by then we will surely have become something that won’t worry too much about the death of a piddling little star…
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### Author:  [@Small\_Clanger](https://boards.straightdope.com/u/Small_Clanger)
#### Post date: [March 11, 2004, 2:57pm UTC](https://boards.straightdope.com/t/when-the-sun-burns-out/233681/3 "2004-03-11T14:57:30Z")
Well, conventional thinking is that we’ve got five _billion_ years to think about it. Then the sun will expand into a red giant before petering out.
We’ll have been clobbered with plenty of extinction level(?) events before then.
Don’t loose any sleep about the Sun. Worry about those Earth crossing asteriods instead.
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### Author:  [@db4530](https://boards.straightdope.com/u/db4530)
#### Post date: [March 11, 2004, 3:03pm UTC](https://boards.straightdope.com/t/when-the-sun-burns-out/233681/4 "2004-03-11T15:03:04Z")
[joke]
Scientist (lecuting to a large crowd): The sun will burn out in a billion years!
A woman in the back row jumps up and screams in a horrified voice: What did you say?
Scientist: The sun will burn out in a billion years.
Woman: Oh, thank god. I thought you said a MILLION.
[/joke]
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### Author:  [@Anaamika](https://boards.straightdope.com/u/Anaamika)
#### Post date: [March 11, 2004, 3:41pm UTC](https://boards.straightdope.com/t/when-the-sun-burns-out/233681/5 "2004-03-11T15:41:24Z")
Centerpiece of one of Isacc Asimov’s short stories: _The Last Question_. How does one reverse entropy?
In the story they kept asking the Universal AC, which became the Cosmic AC, and then the Galactic AC. Eventually Man died out and there was nothing left but the AC…who eventually decided the matter by doing it, that is restarting life. It was supposed to show that God was our own invention, I think. A very good question.
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### Author:  [@GorillaMan](https://boards.straightdope.com/u/GorillaMan)
#### Post date: [March 11, 2004, 3:45pm UTC](https://boards.straightdope.com/t/when-the-sun-burns-out/233681/6 "2004-03-11T15:45:34Z")
Before it burns out, the sun will swell into a red giant, which will swallow up the earth. So no, there’s no way life on earth could survive it in any way.
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### Author:  [@Skytiger227](https://boards.straightdope.com/u/Skytiger227)
#### Post date: [March 11, 2004, 3:55pm UTC](https://boards.straightdope.com/t/when-the-sun-burns-out/233681/7 "2004-03-11T15:55:32Z")
However, if you would like to experience what it would be like when the sun becomes a red giant and burns out, first go to your local tanning salon and stay in for the maximum amount of time. Then go find a walk in freezer. Ta-Da! :eek:
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### Author:  [@Bytegeist](https://boards.straightdope.com/u/Bytegeist)
#### Post date: [March 11, 2004, 3:59pm UTC](https://boards.straightdope.com/t/when-the-sun-burns-out/233681/8 "2004-03-11T15:59:08Z")
> [@welloso](#):
>
> I know it might not happen today or tomorrow , but it is going to happen one day they say , the sun will burn itself out . Has there been any research into what will happen when that day arrives , or is it because the time is so far off we may be able to deal with it then due to advances in technology in the next few billions of years , no one has botherd to look into it ? That is if we havent all killed each other by then .
As **Clanger** says, we have about 5 billion (5 x 10[sup]9[/sup]) years before the sun burns out, when it will exhaust the fuel in its hydrogen-fusing core. However, the sun is also getting gradually hotter with time, and so its threat to our existence (as if there weren’t _enough_ of those already) will come sooner. I’ve read estimates that we have about 2 to 3 billion years before the oceans start to evaporate, and life on Earth must come to an end.
As Clanger further points out, that’s a long time. Well before the sun makes a nuisance of itself, we’ll have to face some asteroid collisions. This though is something that could be prevented with technology, in principle, though not with anything we have ready today.
Even if asteroids cease to be a worry, there’s still the fact that a few billion years is — have I mentioned this yet? — a really _really_ long time, longer than any species has ever endured before. We can be pretty confident that humanity will no longer be here by then. Our species will either go extinct, or evolve into something else (many something elses probably), or transform itself deliberately into a different kind of life. By the year 2 billion A.D., our remote descendants might have no need for water or light or oxygen or proteins, and could live happily on Pluto.
That’s all fanciful speculation of course. More than likely, we’re toast.
If, for some reason, there are still sapient hominids around in that distant future, and if they are still dependent on earth-like conditions in order to live, then obviously they have a serious problem on their hands. If they want to survive, they’ll have to find a another habitable planet around a sun-like star. Fortunately, the Milky Way galaxy has produced and is producing lots of these stars, and they aren’t hard to find. Earth-like planets, on the other hand, are presently beyond our ability to find, but that’s another challenge that technology might be able to solve one day.
But more than likely, they’ll be toast.
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### Author:  [@JRDelirious](https://boards.straightdope.com/u/JRDelirious)
#### Post date: [March 11, 2004, 4:04pm UTC](https://boards.straightdope.com/t/when-the-sun-burns-out/233681/9 "2004-03-11T16:04:02Z")
> [@db4530](#):
>
> [joke]
> Scientist (lecuting to a large crowd): The sun will burn out in a billion years!
> A woman in the back row jumps up and screams in a horrified voice: What did you say?
> Scientist: The sun will burn out in a billion years.
> Woman: Oh, thank god. I thought you said a MILLION.
> [/joke]
Although, in a real-science twist on this, stellar evolution may lead to a change in the conditions on Earth such that our familiar ecosystems (be they land or sea, hot or cold, wet or dry) cannot survive and something entirely else should have evolved, well before the Red Giant phase proper.
In any case, as **Malacandra** mentions, the likelihood is that be it by natural causes or induced action, whatever is around to observe that the weather this year is really, really, REALLY bad is _not_ going to be what we now call _H. Sapiens_.