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

I am aware that most of the earths potential heat is "trapped" , for lack of a better word , within the core as nuclear energy, but my point that given enough time (Eternity) even the protons within the core will ultimately decay and vanish from the universe, proton decay is said to be some 10 to the 35^ a long long long time but how long is still the point of this thread. Heck guys what great and informative posts from most of you out there

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.

Not quite, there are some places on earth where a 20-30 degree drop happens simply because of nightfall but most of the land on earth only experiences a small drop of about 5-10 degrees at night. Even in places with the large drop, we cannot expect the cooling to continue at the same rate. There are places on earth that experience night for months on end and the cooling slows almost to a halt at lower temperatures. The reason being that we have an atmosphere on earth. On the moon though, you could expect much further cooling the longer a night lasts.

I think the Earth would freeze very quickly, at least at the surface. The background temperature of space is about -270 degrees K. I am not enough of a mathematician to calculate how long it would take, but it would be on a scale of weeks to months rather than billions of years. The interior would take longer though, because as others have mentioned, the interior of the planet is kept hot by the slow radioactive decay of elements like Uranium.

Well it takes 8.3min for the light of the sun to get here. So within that time the earth will start cooling down rapidly. Actually I think it will only take minutes though there is no way to prove this and there is no good reason TO prove this.

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?
Tidal forces. Gravity pulls slightly harder on the "near" side than the "far" side, and multiple bodies in the vicinity (other moons) pull in different direction. The result is that the moon "flexes" slightly, and the stress of this releases a lot of energy. The energy ultimately comes from the kinetic energy of the bodies orbiting in the system.

Tidal heating like this is interesting because (among other reasons) it provides the possibility of a "warm" planetary body far outside what's normally thought of as a star's habitable zone.

Tidal heating like this is interesting because (among other reasons) it provides the possibility of a "warm" planetary body far outside what's normally thought of as a star's habitable zone.

Like what Jupiter does to Europa?

I think the Earth would freeze very quickly, at least at the surface. The background temperature of space is about -270 degrees K. I am not enough of a mathematician to calculate how long it would take, but it would be on a scale of weeks to months rather than billions of years. The interior would take longer though, because as others have mentioned, the interior of the planet is kept hot by the slow radioactive decay of elements like Uranium.

Are you refering to the surface of the earth?, if so I agree with you, but for the entire earth to freeze would, in my opinion, take billions of years to feeze down to the very core of the earth

I am aware that most of the earths potential heat is "trapped" , for lack of a better word , within the core as nuclear energy, but my point that given enough time (Eternity) even the protons within the core will ultimately decay and vanish from the universe, proton decay is said to be some 10 to the 35^ a long long long time but how long is still the point of this thread. Heck guys what great and informative posts from most of you out there
Well, to begin with the heat would drop sufficiently for the core to solidify - and I have no idea how much heat it takes to maintain its liquid nature. Even then it would remain "warm" for quite a long time.

The half-life of the 4 main isotopes (K-40, U-235, U-238 and Th-232) range from 0.7 billion years up to 14 billion years.
So the speed of the drop in heat output will depend upon the abundance of the isotopes.

There are other sources of the heat in the core, but these are thought to be the main ones - and mainly Uranium 238 I think - which has a half-life of 4.5bn years (so half of it has decayed since the earth formed).

All in all I think you are talking of the order of 10s of billions of years before the earth's core soldifies (possibly much longer)... and even then it would still be reasonably warm for 10s of billions of years or more.
To drop to within a few degrees of ambient space could even take a trillion years or so, I'd have thought.

Tidal forces. Gravity pulls slightly harder on the "near" side than the "far" side, and multiple bodies in the vicinity (other moons) pull in different direction. The result is that the moon "flexes" slightly, and the stress of this releases a lot of energy. The energy ultimately comes from the kinetic energy of the bodies orbiting in the system.

Tidal heating like this is interesting because (among other reasons) it provides the possibility of a "warm" planetary body far outside what's normally thought of as a star's habitable zone.

Tidal forces do not induce heat. Do not be ridiculous boy.

Maybe you could try to learn a little bit about a topic before posting bullshit? It's not like it should take a lot of mental effort for you to google "tidal heating" and read the first few results.

http://www.planetaryexploration.net/jupiter/io/tidal_heating.html
http://en.wikipedia.org/wiki/Tidal_acceleration
http://www.daviddarling.info/encyclopedia/T/tidalheating.html

But thanks for playing...

My idea in this thread was to mentally consider that the universe had become completely empty, except for our tiny and now very lonely planet. Entropy would continue to happen until an infinite entropic state occurs. Then and only then would the earth the entire universe be at an infinite entropic state, resulting in a temperature of absolute zero for everything.

Maybe you could try to learn a little bit about a topic before posting bullshit? It's not like it should take a lot of mental effort for you to google "tidal heating" and read the first few results.

http://www.planetaryexploration.net/jupiter/io/tidal_heating.html
http://en.wikipedia.org/wiki/Tidal_acceleration
http://www.daviddarling.info/encyclopedia/T/tidalheating.html

But thanks for playing...

In all the years I have studied physics, I have never heard of it.

I apologize.

In all the years I have studied physics, I have never heard of it.

I apologize.

From what I gather Tidal Force is friction.... So I would doubt you never heard of it in physics. But perhaps you only learn that in Astronomy? :shrug:

From what I gather Tidal Force is friction.... So I would doubt you never heard of it in physics. But perhaps you only learn that in Astronomy? :shrug:

Gravity causing friction under trhe surface of the earth is more a subject you would learn about in astrophysics.

Gravity causing friction under trhe surface of the earth is more a subject you would learn about in astrophysics.

Physics never has been my forte. Though I never tried. I just think I am not smart enough for that.

Each to their own. I always had problems in biology.

Then and only then would the earth the entire universe be at an infinite entropic state, resulting in a temperature of absolute zero for everything.

For the universe or any object in it to be at absolute zero, you would need the possibility as you say of "infinite entropy". In order to have infinite entropy, you would need infinite time and you would also need to prove the assumption that the universe will expand forever.

For the universe or any object in it to be at absolute zero, you would need the possibility as you say of "infinite entropy". In order to have infinite entropy, you would need infinite time and you would also need to prove the assumption that the universe will expand forever.

Those things simply cannot be proved, just like it is up to now impossible to PROVE how the Big Bang happened and what as yet unknown force drove the universe outward from the singularity against the huge gravity field of the primordial universe, contained in the singularity moment