what if the sun just stopped no light no heat nothing, would we be immediatly frozen or would it be gradual?
Quasi-educated guess time… IIRC, if the sun just “went out” like a light bulb, we’d still have approx. 3 minutes of sunlight left (because that’s how long it’d take the last rays of light to reach us). After that, it’d get really cold really fast. However, the sun will not just “go out”, it’s more likely to move to the inevitable red giant stage that stars go through, at which time Mercury and probably Venus would be engulfed in the sun (hence vaporized), and Earth and it’s inhabitants would be turned to crispy critters. 
-Dani
Well, after about 8 minutes of regular sunlight, it would immediately be night time, and stay that way.
I’m not sure if I’d be right to equate it to nighttime; maybe night still has some reflected sunlight, but things would eventually cool down and in a few weeks/months, we’d all be dead.
I think.
This is just guessing…
The 8 (and a bit) minutes is correct, but it wouldn’t be like night at all. At night half the earth is still being heated by the sun. If that was suddenly all gone, I can’t believe it would take more than a couple of minutes for the air to liquify and then turn solid.
Remember to wear your thermals
If the Sun suddenly stopped, as stated it would take 8.5 minutes before we found out. Then it would go very dark. Even the moon would not be visible. The atmosphere and oceans has a considerable specific heat capacity so it should take a while, a few days?, before it started cooling. Arm waving, within a week the atmosphere would be royally screwed, first storms then no wind as pressure normalises. Initially all the water would come out of suspecion to form massive flooding then freeze as temperatures would drop well below freezing and continue to drop. In a month or so you would get liquid Nitrogen/Oxygen forming.
But, if the Suns’ nuclear core stopped it would disrupt its thermodynamic equilibrium. It would start collapsing under gravity immediately. This would drive the core pressure up and restart nuclear reactions. It normally takes about a million years for a photon to leave the core but this would be catastrophic reburn, similar to a helium flash in larger stars undergoing shell burning. I don’t know what exactly would happen but a few minutes after the Sun stopped it would send out a considerable number of neutrinos and photons plus a very strong solar wind. X-class coronal mass ejections would like a candle in the wind compared to this.
Forget about the atmosphere cooling, chances are it would be largely stripped by the shock wave.
Phew! Better hope that it doesn’t happen then.
At night, there is negligible amount of heat transfer from the day side of the earth to the night side. What mechanism could do that? Convection would require air to move halfway around the world in a matter of hours, and all other methods would be even less efficient.
So if the sun suddenly stopped radiating any energy, it would be just like night. I’d guess that at the equator, it would still take several days for the temperature to drop below freezing.
Humans could survive indefinitely, though not all of us. Population will be limit by how much food we can grow using artificial lighting, as well as heating power for our habitats.
Of course, there is no known method by which the sun would stop radiating light, so I think we can rest easy.
But what would happen if the earth stopped rotating?
And only one side faced the sun?
Well, it would be nighttime permanently on one side, and daytime permanently on the other. Vegitation on the dark side would probably die for the most part, and the same might be the case for the bright side. Furthermore, a lot of animals would be pretty messed up about it. Gravitiational pull would also be (marginally?) greater, because it would not be countered by G-forces. Other than that, you could start one hell of a holiday resort if you were to find yourself just over the light border.
Thanks Coldfire(are you really naked?)
What about the tides then?
And the only place to live would be the moderate area right between the dark and light sides.
Would the wind stop too?
First, the Sun ain’t gonna go out anytime soon. It’ll be a billion years or so before it runs out of hydrogen, swells into a red giant and bakes us.
Second, if it suddenly stopped fusing hydrogen into helium, it would take roughly 40,000 years for the heat to leak out from the core to the surface. The common idea that it takes about a million years (which I have on my own site) may be wrong; new models show it leaking out faster. We’d know sooner anyway since the Sun would stop producing neutrinos, and we’d detect that pretty quickly.
Third, if it just stopped giving off heat magically, then the Earth would cool fairly slowly, as some people have noted. The Earth would have to radiate away all the heat it already has, and that takes time. Not too much time though! Where I live, the temperature commonly drops 20 degrees or so at night, so I can imagine the temp would go below freezing in less than a week certainly. The oceans do store a vast amount of heat, so that would help. I suspect after a month or so we’d all be dead as the temperature gets too low to sufficiently heat ourselves. Once the temp drops below the liquification point of nitrogen, that’s about it.
If the Earth stopped spinning there would be other problems. You’d never feel the difference in gravity (any more than you would if you went to the north pole, where centripetal force is also zero). There would be some heating of the night side from the day side via winds, but that may not be terribly efficient. I have not seen models of this though. I suspect it would always be windy, as air moves from hot side to cool, but after a while an equilibrium might be reached. This is kinda neat, actually. I’ll have to think about it some more.
Half way around the world? I don’t think that we only have a brief moment of sunlight at high noon (unless you live in the UK)…well more than half the atmosphere of the earth is always being heated by the sun, and it still gets cold at night time…
Sorry, but I can’t see us moving from our relatively warm position near to the sun, being shoved into an environment about -270 degrees colder, and taking a few days to cool down…
Dylan, let me explain. At night things start to get colder, right? But they don’t drop to absolute zero right away, right? Why is that? Your theory is that the sun is still heating the other side of the earth and that keeps the night side warmer.
But that’s not what’s happening. The heat from the day side would have to be transferred somehow to the night side. That could happen by convection…the heat could simply travel through the earth. But the earth is a pretty good insulator. Remember, only a few miles down the interior of the earth is molten rock.
The other way would be for warm air to travel from the day side to the night side. But we know that doesn’t happen, because there would have to be tremendous winds. The terminator travels at ~1000 miles per hour. Masses of air don’t move that fast.
No, the real reason is that it would take quite a long time for the earth to radiate all it’s heat into interstellar space. Even when the surface is so cold that the atmosphere snows out the interior would still be molten for millions–probably hundreds of millions–of years. See, the earth is very well insulated by trillions of cubic miles of vacuum. The only way the earth can gain or lose heat is through radiation. OK, we do lose a tiny tiny amount of heat from air escaping into space. But not much.
The biggest buffer for heat is the oceans. It takes hours for ice cubes to freeze in your freezer. It would take weeks for the oceans to freeze solid. And even at equilibrium there would be some liquid areas at the deep sea vents. Life could probably continue to exist down there for millions of years after the sun went out. The trouble would be that each community would be isolated, with no chance for repopulation if a vent quit. Eventually all the populated vents would stop, while newly created vents would not be stocked.
Now, I see big problems if the earth stopped rotating. Let’s say that it was done safely, with inertial dampers and such. The big problem I see is that the atmosphere and hydrosphere would begin to condense on the dark side. Air and water glaciers would form on the dark side, while the oceans would boil on the day side.
We’d have interesting weather for while, with a huge high-pressure zone at the sun pole and a huge low-pressure zone at the night pole. The night pole would constantly snow…first water ice, then CO2, then nitrogen and oxygen. After a while, all the volatiles would be trapped in glaciers on the night side. So the idea of life continuing in the temperate region around the terminator won’t work, since there would be no atmosphere. Yes, some of the volatiles would sublimate, but we’d essentially have a vacuum.
I have no idea how long it would take for the atmosphere to freeze out. I suspect it would be within a year or two, but I’m just guessing.
The Earth will stop rotating due to tidal forces, correct? Just as the moon has stopped rotating with respect to Earth. So it will happen very gradually (in fact, it’s happening as we speak!!!), and presumably evolution will take its course; vegitation of some sort would most likely survive, especially on the “day” side.
Lemur866, why would the atmosphere freeze? You mention that it would take quite a while for the oceans to freeze if the sun went out; obviously the problem would be nowhere near as severe if the Earth stopped rotating. My offhand (and layperson’s) guess is that you paint to drastic a picture. I don’t know that we’d reach an equilibrium between the day side and the other side. Though it’s not exactly equivalent, the atmosphere doesn’t start condensing at the South pole during winter…
So…What if the moon got closer?
I am just full of questions.
What if the earth suddenly started rotating the Opposite direction from what it does now?
Warning!!! Spoiler
Ahh, but what if there are little dark matter birds in our sun draining the heat off like in Stephen Baxter’s Ring. The whole premise was that dark matter couldn’t interact with baryonic(sp?)matter except in extreme cases of gravity(I.e middle of suns, black holes, ect). Well, the Dark matter had evolved somehow into life that feared unstable suns, so it deliberately cooled off all the suns in the universe so that they would not have to worry about supernovas and such. (I am probably messing this up badly). (in the book it took 10 million years for photons to get out of the middle of the sun…its Sci-fi though…) The dark matter birds had enough influence in the gravity well of the sun to drain heat off the particles as it passed through them, cooling the sun and shortening its lifespan. (5 million years from the year 3000 or so and it went into its red giant phase).
It’s sci-fi, so I definately would not take it for reality.
Physicists Fred Adams and Greg Laughlin wrote a science book called The Five Ages of the Universe: Inside the Physics of Eternity. In one chapter, they explored a far more plausible scenario: A near-collision with another star causing the Earth to leave its orbit (and the solar system) and wander the Milky Way as a rogue planet. It would take more than two decades before the Earth actually left the solar system, but nearly all surface life would be dead and frozen before passing the orbit of Jupiter.
Lemur866 got it right, according to that book. I liked the part where they pointed out that the life around hydrothermal vents could just keep on going for millions of years, not even aware of what had happened…
You might be interested in A Pail of Air by Fritz Leiber, originally published in Galaxy and collected in several anthologies. See http://ourworld.compuserve.com/homepages/fizzer/poa.htm for a ref to the collection under the same title.
In the story, a family survives such a catastrophe for quite a while using only low-tech means.
Well, it might take longer than I thought for the air to precipitate if the earth stopped rotating. The biggest problem would be the oceans freezing on the dark side and boiling on the day side. You’d get several mile thick glaciers at the dark pole, while the day-side oceans boiled off.
However, there could be a loophole. If the dark-side glacier slumps enough, you could have a constant conveyer belt into the twilight areas, providing enough meltwater to sustain life. And if the water glaciers did this, of course the frozen air would melt much sooner, if it ever did freeze. I guess it would depend on the plasticity of ice at the temperatures and pressures of the dark side at equilibrium.
While we still had an atmosphere, we’d have some very different weather patterns, since we’d have a constant flow of warm moist air rising from the hot pole, while cold dry air flows toward the hot pole underneath. When the warm moist air reaches the dark side it starts to rain. When in gets cold enough it starts to snow. But snow that fell on the dark side would never melt, it would accumulate
The biggest question is exactly how cold the dark pole would get. Cold enough to freeze water certainly. But maybe we’d keep our atmosphere. But our oceans would be in trouble. The thing that might save us is that the high pressure of the glaciers would melt the water at the bottom, causing the glaciers to move.
If the sun went out, the stars would sure be pretty!
On a more serious note, the earth will one day have one side facing the sun. Any body obiting another will eventually do the same, as the moon already has one side facing the earth. It was thought that Mercury had already stopped rotating, but it still has some rotation left.