How fats would a planet cool down if moved from sun?

2000AD · Post by **2000AD** » 2003-03-23 03:09pm

If you moved a planet, let's say it's identical to Earth, away from it's sun and into outer space away from any other heat sourse, how fast would it cool down?

Durandal · Post by **Durandal** » 2003-03-23 04:11pm

2000AD wrote:If you moved a planet, let's say it's identical to Earth, away from it's sun and into outer space away from any other heat sourse, how fast would it cool down?

Very quickly.

Captain Jack · Post by **Captain Jack** » 2003-03-23 04:14pm

The same rate as it cools at night I guess.

2000AD · Post by **2000AD** » 2003-03-23 04:44pm

Just how fast? Minutes? Hours? Days?

Stormbringer · Post by **Stormbringer** » 2003-03-23 04:47pm

2000AD wrote:Just how fast? Minutes? Hours? Days?

Days at most assuming you moved it away suddenly. If you moved it slowly it would depend on how fast you moved it.

Post by **NecronLord** » 2003-03-23 04:47pm

Until it all equallised with deep space temprature? millions of years, (the core would need to freeze). Until it's entire surface became siberia/alaska but worse? Hours, maybe a day. The seas would remain habitable for a day or so afterwards, and the very deep oceans a few months to years. After a few weeks the atmosphere would begin to condense...

2000AD · Post by **2000AD** » 2003-03-23 05:00pm

Assuming the planet just instantaneously moves, are Necronlords calcs/estimates applicable?

Stormbringer · Post by **Stormbringer** » 2003-03-23 05:23pm

2000AD wrote:Assuming the planet just instantaneously moves, are Necronlords calcs/estimates applicable?

It'd take a little longer than that for it to hit Alaska Siberia temperature. But no more than a couple of days.

2000AD · Post by **2000AD** » 2003-03-23 05:31pm

Thanks. I'm planning on this event happening in my (postponed) fanfic. Just wanted to make sure that all my guys on the planet wouldn't get super chilly before they had a chance to get off.

Stormbringer · Post by **Stormbringer** » 2003-03-23 05:53pm

2000AD wrote:Thanks. I'm planning on this event happening in my (postponed) fanfic. Just wanted to make sure that all my guys on the planet wouldn't get super chilly before they had a chance to get off.

The Earth would probably start cooling much like it would at night and just not stop.

Post by **Darth Wong** » 2003-03-23 06:35pm

The acceleration necessary to shove a planet into interstellar space in a reasonable period of time would kill everyone on the planet almost immediately. Cooling would not be an issue.

Pu-239 · Post by **Pu-239** » 2003-03-23 07:31pm

Darth Wong wrote:The acceleration necessary to shove a planet into interstellar space in a reasonable period of time would kill everyone on the planet almost immediately. Cooling would not be an issue.

Well the planet could have been just beamed there, though that's wandering into technobabble.

The Dark · Post by **The Dark** » 2003-03-23 07:34pm

Pu-239 wrote:
Darth Wong wrote:The acceleration necessary to shove a planet into interstellar space in a reasonable period of time would kill everyone on the planet almost immediately. Cooling would not be an issue.
Well the planet could have been just beamed there, though that's wandering into technobabble.

*shrug* someone puts a giant solar sail in a geosynchronus orbit between the planet and its star. World's stuck in perpetual shade. A bit less technobabblish than the beaming, and doesn't require a shove to interstellar space.

Einhander Sn0m4n · Post by **Einhander Sn0m4n** » 2003-03-23 07:38pm

The Dark wrote:
Pu-239 wrote:
Darth Wong wrote:The acceleration necessary to shove a planet into interstellar space in a reasonable period of time would kill everyone on the planet almost immediately. Cooling would not be an issue.
Well the planet could have been just beamed there, though that's wandering into technobabble.
*shrug* someone puts a giant solar sail in a geosynchronus orbit between the planet and its star. World's stuck in perpetual shade. A bit less technobabblish than the beaming, and doesn't require a shove to interstellar space.

Or someone could deploy an Orbital Nightcloak system similar to the type the Empire is known to possess (hint hint!)

Durandal · Post by **Durandal** » 2003-03-23 07:50pm

Pu-239 wrote:
Darth Wong wrote:The acceleration necessary to shove a planet into interstellar space in a reasonable period of time would kill everyone on the planet almost immediately. Cooling would not be an issue.
Well the planet could have been just beamed there, though that's wandering into technobabble.

I think you're missing the point. The Earth is currently orbiting the Sun. It is orbiting at a certain velocity. If we just beam it out into space, everyone will go flying off the surface. Well, some poor people will end up buried in the ground, but everyone would die, nonetheless. Conservation of momentum.

Grand Admiral Thrawn · Post by **Grand Admiral Thrawn** » 2003-03-23 08:29pm

The thread is about how fast it would cool down. Maybe the population is beamed up, they beamed down when the Earth arives in Nowhere.

Or the sun is moved.[/quote]

SyntaxVorlon · Post by **SyntaxVorlon** » 2003-03-23 11:07pm

Quite a bit of trouble to kill everyone through transportation, the fact that it would be transported with everyone transported as well?
That's unneeded cruelty just to make everyone freeze to death.
Also all that talk of CoM depends entirely upon whether or not you consider the free bodies on the surface as truely not part of it's mass, if not then how are they too getting transported, beamed, whatever? If whatever is beaming them off into space does so to the entire planet atmosphere and all the whole of their momentum would end up in the same place as the planets.

I've always wondered how a core could truly freeze with such intense grav pressure constantly being exerted.

Post by **fgalkin** » 2003-03-24 12:08am

Pu-239 wrote:
Darth Wong wrote:The acceleration necessary to shove a planet into interstellar space in a reasonable period of time would kill everyone on the planet almost immediately. Cooling would not be an issue.
Well the planet could have been just beamed there, though that's wandering into technobabble.

Why? Just use a farcaster.

Have a very nice day.
-fgalkin

Kuroneko · Post by **Kuroneko** » 2003-03-24 06:56am

2000AD wrote:If you moved a planet, let's say it's identical to Earth, away from it's sun and into outer space away from any other heat sourse, how fast would it cool down?

That's a pretty interesting question; I'd like to know myself. I'm sorry I don't currently have the time for a full treatmeant.

Assuming the planet stops receiving radiation from space (for whatever reason -- instant transportation or blockage) and ignoring geothermal effects completely, let t be time in seconds, Q be heat and T temperature, so dQ/dt = -keT^4, k = 5.6703e-8 J/(s m^2 K^4) (Stefan-Boltzmann constant), e emissivity, dT = dQ/C, where C is surface heat capacity per area. This is very easily separable, dt = -C/(ke) T^-4 dT, so that t = (C/3ke)T^-3, ignoring initial conditions.

Earth's albedo is 0.36 +/- 0.06 [CRC Handbook of Chemistry and Physics, 1977], meaning emissivity is about 0.64. It would be nice to know what C is... assuming typical night-time and day-time temperatures at 283K and 293K, respectively [1], e*12hr = (C/3k)(1/283^3 - 1/293^3), i.e. (C/3k) = 6.3e12 K^3 s.

Earth's average surface temperature is 288K. For average surface temperature to reach 271K, freezing point of typical seawater, it would take about 6.3e12/0.64 * (1/271^3 - 1/288^3) seconds, which is twenty-three hours. Please note that this is the average temperature; desert areas should be significantly below this, while ocean areas above.

Still, at this point, surface heat capacity (per area) should start to change significantly due to the formation of ice. On the other hand, emissivity will be higher for the same reason, in addition to much clearer skies. If anyone wants to make a reasonable estimate of how the temperature will fall past this point, please do.

Post by **NecronLord** » 2003-03-24 04:47pm

Durandal wrote:
Pu-239 wrote:
Darth Wong wrote:The acceleration necessary to shove a planet into interstellar space in a reasonable period of time would kill everyone on the planet almost immediately. Cooling would not be an issue.
Well the planet could have been just beamed there, though that's wandering into technobabble.
I think you're missing the point. The Earth is currently orbiting the Sun. It is orbiting at a certain velocity. If we just beam it out into space, everyone will go flying off the surface. Well, some poor people will end up buried in the ground, but everyone would die, nonetheless. Conservation of momentum.

Fine, teleport it into an equivalent orbit around a neutron star.

SirNitram · Post by **SirNitram** » 2003-03-24 06:43pm

Or it could be left to continue in motion at the end of it's transition.. You know, not spontaneously assuming it's going to stop?

Post by **Darth Wong** » 2003-03-24 08:14pm

Kuroneko wrote:Earth's average surface temperature is 288K. For average surface temperature to reach 271K, freezing point of typical seawater, it would take about 6.3e12/0.64 * (1/271^3 - 1/288^3) seconds, which is twenty-three hours. Please note that this is the average temperature; desert areas should be significantly below this, while ocean areas above.

The thermal "delay" of the oceans is around six months. This treatment neglects heat conduction from underlying mass.

Kuroneko · Post by **Kuroneko** » 2003-03-24 09:36pm

Darth Wong wrote:The thermal "delay" of the oceans is around six months. This treatment neglects heat conduction from underlying mass.

Well, I admit it was the epitome of 'back-of-the-envelope' calculations, explictly ignoring geothermal effects.

Still, throughout an average 10K temperature variation from day to night, the Earth radiates about 1.1e6 J/m^2 into space for each 1K surface temperature drop, and there's no heat loss from Earth en masse except for that. By no means do I expect this correlation (and that's all it really is) to hold up indefinetely, but I feel that it shouldn't be too bad in the range I extended it to, up to the point past which I felt it breaks down significantly.

As for a better model, I'm still interested in this problem, but I'm afraid that shall have to wait until I'm neither busy nor running mostly on caffeine and sheer willpower.

2000AD · Post by **2000AD** » 2003-03-25 05:28am

Just to clarify things, the planet in question is just subjected to <technobabble> and mysteriously teleports to some region in outer space, away from a heat source, instantaneously.

Post by **NecronLord** » 2003-03-25 08:33am

SirNitram wrote:Or it could be left to continue in motion at the end of it's transition.. You know, not spontaneously assuming it's going to stop?

The angular momentum that dissapeared would cause problems, Big ones.

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How fats would a planet cool down if moved from sun?

How fats would a planet cool down if moved from sun?

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