In the absence of the sun, how long would it take for earth freeze solid

[Green Destiny]

Geothermal energy induced by gravitational forces accounts for a couple of degrees at our present temperatures, it would never freeze entirely - until the Earth's core stabilized...if that's possible.

Induced by gravitational forces? Is that right? I'm not a geologist, but I would have assumed for knowing the laws of physics, that gravitation plays no noticable effects other than gravitational attraction between two macroscopic bodies. How does gravity induce heat?

Most of the Earth's heat is caused by a natural insulation, and weak force relations to decays of radiation. How does gravity play such a role, if it even does?

 

[NO1]

Induced by gravitational forces? Is that right? I'm not a geologist, but I would have assumed for knowing the laws of physics, that gravitation plays no noticable effects other than gravitational attraction between two macroscopic bodies. How does gravity induce heat?

Most of the Earth's heat is caused by a natural insulation, and weak force relations to decays of radiation. How does gravity play such a role, if it even does?

When atoms goes from an excited to base state, they emit photons with frequency and energy. Energy = Heat ? From GTD

 

[Green Destiny]

When atoms goes from an excited to base state, they emit photons with frequency and energy. Energy = Heat ? From GTD

Right, well, gravitational time dilation is nothing to do with atomic excited states.

 

[Green Destiny]

What you're describing is what is called ''quantum jumps'' and in some cases result in the spontaneous emmision of radiation. Gravity plays nearly no role on the fundamental level between particles.

 

[NO1]

If you read everything, you would have seen Pound-Rebka Experiment which explains it?

 

[joepistole]

No it's not. Jupiter made of gas so it's hard to envisage whet would be erupting out of what. You could describe the red spot as a storm.

It also vanishes from time to time.

 

[Green Destiny]

That experiment involves measuring the gravitational potential between two points in the sphere of the earth. One would be found to have a clock running faster and a clock running slower in the basement.

Explain to me how that describes atomic excited states?

 

[NO1]

Well, the gravitational forces cause release of photons from atoms which are equal to energy. I made an assumption that Energy= Heat. I cant back up my claim saying that gravity is thermodynamic energy.

 

[Green Destiny]

I cant back up my claim saying that gravity is thermodynamic energy.

I didn't think you could.

 

[Fraggle Rocker]

It has taken several billion years for the earth's solid inner core to cool to its current temperature of about 5700K or almost 10,000F. Without the sun's radiation the rate of cooling would increase, but it will still take a long time to reach freezing temperature. I assume that's what you mean. Since it is in a solid state, it is already "frozen." I'll let somebody else do the math, but I'm sure it would be thousands of years, probably much more.

But if you are just talking about the surface, that wouldn't take long to freeze at all, at least the land portion. The temperature in any given location can drop twenty or thirty degrees in the twelve hours when it's not turned toward the sun. If the sun never reappears, presumably it will continue falling at more or less the same rate.

The oceans will take longer, because of water's fabulous property of being less dense in its solid state. As the oceans freeze the ice floats to the top, insulating the liquid water underneath. This is why marine animals can live under the north polar ice cap. It will take quite a bit longer for the oceans to freeze solid. I'll let somebody else do that math too!

Assuming we can tap the geothermal energy, we might be able to keep civilization going for quite a while, as we put all of our resources into developing interstellar travel. Of course there will be considerable panic and social unrest, since we can't possibly build enough shelters for all of us as quickly as we'll need them.

 

[Green Destiny]

It has taken several billion years for the earth's solid inner core to cool to its current temperature of about 5700K or almost 10,000F. Without the sun's radiation the rate of cooling would increase, but it will still take a long time to reach freezing temperature. I assume that's what you mean. Since it is in a solid state, it is already "frozen." I'll let somebody else do the math, but I'm sure it would be thousands of years, probably much more.

But if you are just talking about the surface, that wouldn't take long to freeze at all, at least the land portion. The temperature in any given location can drop twenty or thirty degrees in the twelve hours when it's not turned toward the sun. If the sun never reappears, presumably it will continue falling at more or less the same rate.

The oceans will take longer, because of water's fabulous property of being less dense in its solid state. As the oceans freeze the ice floats to the top, insulating the liquid water underneath. This is why marine animals can live under the north polar ice cap. It will take quite a bit longer for the oceans to freeze solid. I'll let somebody else do that math too!

Assuming we can tap the geothermal energy, we might be able to keep civilization going for quite a while, as we put all of our resources into developing interstellar travel. Of course there will be considerable panic and social unrest, since we can't possibly build enough shelters for all of us as quickly as we'll need them.

The earths insulation provides very little heat for the surface. If the sun disappeared, it's quite sure that earth would freeze over, relatively quite quickly. Space is a cold place, as i said.

 

[Shadow1]

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uuh, i think, in 5 years, the life on earth, will be ruined, i mean, plants needs light to gorw, or most of them, we can make lams or something, but, we are already going out of fuels, anyway, a short answer, we will be screxed in a very short time. but some life forms, may keep existing, those life forms that don't need light, for example the deep ocean life forms.
you can't really predict preicly.

 

[Shadow1]

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but why bother? your question have no sense, everything in the univerce desepear, expet earth??

 

[fedr808]

That is an amazingly hard question to answer correctly.

Thermodynamics, different densities, wind currents, change in pressure as altitude changes, there are so many factors.

 

[raptorttail]

Again, most of the internal heat generated by the Earth is from radiation. The presence or absence of the sun has no impact on this internal heat source. the Earth would not 'Freeze Solid'...it can't.

The physical properties of elements do not alter. What happens on the surface of the Earth is irrelevent as to what is going on within the atoms that make up the Earth. Radioactive decay continues ....energy....heat.

An atom of a heavy element has the same half life regaredless of where it is located...in a Star, on an asteroid or inside the Earth. Pick up a chunk of Uranium and it emits radiation...inside the Earth these elements do the same. They never stop. the reason you don't fry near a nuclear source is because you are shielded and not because the radiation stops. The energy is released by atoms...heat energy builds if confined...happening inside our planet for 4 billion years and will continue as long as the Earth exists.

 

[Sarkus]

uuh, i think, in 5 years, the life on earth, will be ruined, i mean, plants needs light to gorw, or most of them, we can make lams or something, but, we are already going out of fuels, anyway, a short answer, we will be screxed in a very short time. but some life forms, may keep existing, those life forms that don't need light, for example the deep ocean life forms.
you can't really predict preicly.

Lot shorter than 5 years I'd have thought, to merely "ruin" life.

From what I've read (a while ago - and I can't recall the source, although still looking): by the end of the first week the surface temp would be roughly zero-Farenheit on average, and by the end of the first year it would dip down to about -100 F.
The oceans would freeze quite quickly, although this would actually protect the very deepest parts where life... of sorts... could continue.
Humans could survive but would need a fuel source - with either geothermal or nuclear being the obvious ones that are currently available. And they would need to live deep enough to protect them from the surface cold. But they would also need a food-source - which wouldn't be too much of a problem if we can grow the right types of protein / carbs in vats (e.g. algae) or maintain food sources deep underground.

Anyhoo - eventually, after millions of years, the surface would reach an equilibrium of around -400F (c.-240 deg-C) - which would be the balance between heat-loss on the surface and heat supplied to surface by the still-molten core.

Not sure where I dug those numbers up from, though... but I recall reading about this sort of thing a while back... research for a sci-fi plot etc.

 

[fedr808]

Thanks sarkus, that was a great answer. It answered more questions than were asked which I appreciated, I never gave much thought to human survival underground or the logistics.

 

[fedr808]

Again, most of the internal heat generated by the Earth is from radiation. The presence or absence of the sun has no impact on this internal heat source. the Earth would not 'Freeze Solid'...it can't.

The physical properties of elements do not alter. What happens on the surface of the Earth is irrelevent as to what is going on within the atoms that make up the Earth. Radioactive decay continues ....energy....heat.

An atom of a heavy element has the same half life regaredless of where it is located...in a Star, on an asteroid or inside the Earth. Pick up a chunk of Uranium and it emits radiation...inside the Earth these elements do the same. They never stop. the reason you don't fry near a nuclear source is because you are shielded and not because the radiation stops. The energy is released by atoms...heat energy builds if confined...happening inside our planet for 4 billion years and will continue as long as the Earth exists.

That's incredibly idiotic, and I may be no expert so if I am totally off base I will eat my words. First off, our core is not radioactive namely because it is made up of one of the more stable elements. The energy radiated by the sun over one acre on average over the period of the day is equivalent to a very small nuclear detonation.

the final evidence is antarctica. It has areas frozen all year round. Now, since the earth is a globe or a sphere, that means that every spot recieves the same amount of energy on average. If we the internal heat or "radiation" as you call it is enough to keep the earth thawed and warm than explain than how antarctica is frozen. Surely if the internal heat can keep the entire crust thawed than antarctica should be entirely melted especially because of the sun being there to help for a large part of the year.

Assuming your theory is right on the fact that there is radiation that would prevent the earth from -400 degrees it would still leave it at around -130 degrees because that is the coldest that Antarctica gets.

 

[Fraggle Rocker]

That's incredibly idiotic, and I may be no expert so if I am totally off base I will eat my words.

You're basically right but there's no need to be rude about it. We're all here to teach and learn.

First off, our core is not radioactive namely because it is made up of one of the more stable elements.

BTW, the primary elements in the earth's inner core are nickel and iron.

 

[Sarkus]

That's incredibly idiotic, and I may be no expert so if I am totally off base I will eat my words.

Get ready with the ketchup!

First off, our core is not radioactive namely because it is made up of one of the more stable elements.

Raptortail is correct.
80-90% of the heat inside the earth is thought to be due to the radioactive decay of isotopes like Uraniums 235 and 238, Potassium 40, Thorium 232 etc that are contained within the mantle. As these isotopes shed their excess energy they radiate heat - keeping the core liquid.

Gravitational forces are thought to account for 5-10% of the core's heat, and heat left over from the formation of the earth also is thought to be around 5-10%. But by far the majority is from radioactive decay. The percentage contributions differ widely depending on who you talk to, but it is widely accepted that radioactivity is the main contributor.

You have to bear in mind that most of the Earth's crust contains radioactive material, with each kg of surface rock giving off heat through radioactive decay equivalent to 10^-9 Watts or so.

The energy radiated by the sun over one acre on average over the period of the day is equivalent to a very small nuclear detonation.

The surface of the earth - i.e. the outer layer on which we live - heats up very fast and cools very quickly... irrespective of what the inside of the earth is doing. The surface is extremely well insulated from the heat of the core - so is hardly affected by the core temperature, and almost entirely driven by the sun. With no sun the equilibrium temp at the surface would be about -400F.

the final evidence is antarctica. It has areas frozen all year round. Now, since the earth is a globe or a sphere, that means that every spot recieves the same amount of energy on average. If we the internal heat or "radiation" as you call it is enough to keep the earth thawed and warm than explain than how antarctica is frozen. Surely if the internal heat can keep the entire crust thawed than antarctica should be entirely melted especially because of the sun being there to help for a large part of the year.

He never said that the core would maintain the temperature on the surface "thawed and warm" - but that the planet (i.e. the internal core) would not "Freeze Solid", as the temp and activity in the core is driven mainly by the radioactive decay of the various isotopes. And this will take billions of years to run down such that the earth's core solidifies.
It also doesn't have much bearing on the surface temperature... and vice versa.
The Earth will therefore NOT drop to the ambient temperature of space (about 4-Kelvin, I think)... but (and I'm still trying to find the source!) to about -400F (-240C, or about 33K).

Assuming your theory is right on the fact that there is radiation that would prevent the earth from -400 degrees it would still leave it at around -130 degrees because that is the coldest that Antarctica gets.

You misunderstood both him and me: he never said the radiation would prevent the earth reaching -400F, and I said that the surface would reach an equilibrium of about -400F... i.e. the surface of the earth would reach -400F while the core would remain at around 10,000F for a few billion years or so.

The -400F on the surface is the equilibrium temp: i.e. at which the heat energy reaching the surface from the core matches the heat energy radiating out from the surface into space.

And the reason the temp of Antarctica (and the night side of our planet, for that matter) doesn't drop to -400F is because of the atmosphere keeping things warmer than would otherwise be the case - not because of the core temp.


So - feel free to chow down on those words.