Loss of heat from the Earth's core

[whuzzwhuzz]

We all know that Earth's core is relatively hotter than the Earth's surface. And with this temperature gradient, there must me a loss of heat from the Earth's core to the surface and then to atmosphere and outer space by convection and radiation. So, how much time it would require for the Earth's surface temp and core temp to be the same? How does Earth's core generate the temp to maintain this temp?

 

[Borek]

Searching forums before posting often yields tons of interesting information:

https://www.physicsforums.com/showthread.php?t=7071

https://www.physicsforums.com/showthread.php?t=156760

Searching web will yield even more.

 

[Andre]

Anyway, concerning ...

And with this temperature gradient, there must me a loss of heat from the Earth's core to the surface and then to atmosphere and outer space by convection and radiation.

that would be about...

Heat flux from Earth’s interior: 0.008 W/m2

Which is practically negliglible compared to the other heat fluxes.

 

[Nik_2213]

http://en.wikipedia.org/wiki/Age_of_the_Earth
"In 1862, the physicist William Thomson (who later became Lord Kelvin) of Glasgow published calculations that fixed the age of Earth at between 20 million and 400 million years.[15][16] He assumed that Earth had formed as a completely molten object, and determined the amount of time it would take for the near-surface to cool to its present temperature. His calculations did not account for heat produced via radioactive decay (a process then unknown to science) or convection inside the Earth, which allows more heat to escape from the interior to warm rocks near the surface.[15]"

Slightly OT: http://en.wikipedia.org/wiki/Geology_of_Venus

"On Earth, plate tectonics allow the escape of heat from the mantle. However, Venus has no evidence of plate tectonics, so the theory is that the interior of the planet heats up (due to the decay of radioactive elements) until material in the mantle is hot enough to force its way to the surface. The subsequent resurfacing event covers most or all of the planet with lava, until the mantle is cool enough for the process to start over."

Think 'Flood Basalts' writ global...

 

[whuzzwhuzz]

Thanks Borek, Andre and Nik for your response. :)

 

[AtomicJoe]

Just going by say a freshly boiled hard boiled egg one notices that it does no take very long
for the core to cool.
Obviously the Earth is bigger than an egg however it also has had a longer time to cool down.
So it seems to me if it were ever to have cooled down it would have done so by now.
That's my guess anyway, correct me if I am wrong!

 

[AtomicJoe]

http://en.wikipedia.org/wiki/Age_of_the_Earth
"In 1862, the physicist William Thomson (who later became Lord Kelvin) of Glasgow published calculations that fixed the age of Earth at between 20 million and 400 million years.[15][16] He assumed that Earth had formed as a completely molten object, and determined the amount of time it would take for the near-surface to cool to its present temperature. His calculations did not account for heat produced via radioactive decay (a process then unknown to science) or convection inside the Earth, which allows more heat to escape from the interior to warm rocks near the surface.[15]"

Slightly OT: http://en.wikipedia.org/wiki/Geology_of_Venus

"On Earth, plate tectonics allow the escape of heat from the mantle. However, Venus has no evidence of plate tectonics, so the theory is that the interior of the planet heats up (due to the decay of radioactive elements) until material in the mantle is hot enough to force its way to the surface. The subsequent resurfacing event covers most or all of the planet with lava, until the mantle is cool enough for the process to start over."

Think 'Flood Basalts' writ global...

So is the surface of Venus molten?
Bit unclear from that but I would like to know!
I understand the atmosphere is very hot there, supposedly due to 'global warming' however if the surface was molten I would expect it to be hot anyway?
Do they take that into account if true? I expect they would have to.
Can anyone clarify, please don't tell me to google it, I don't want to at the moment so if you don't know just say so.

 

[Borek]

So is the surface of Venus molten?

Does it look like molten?

http://sagemission.jpl.nasa.gov/images/gallery/bw_v13.jpg

 

[AtomicJoe]

Does it look like molten?

http://sagemission.jpl.nasa.gov/images/gallery/bw_v13.jpg

That looks like a pub car park near me, are you sure it's Venus?
Lets face it it you had gone to the trouble of sending a probe to Venus you would be able to come up with a better
picture than that!

 

[Ophiolite]

It is most assuredly Venus taken by one of the Russian Venera probes. How long do you think you can keep a probe operating in temperatures hot enough to melt lead and pressures higher than 1,000 psi?

You may wish to look instead at http://commons.wikimedia.org/wiki/Category:Magellan_radar_images_of_Venus" taken from radar imaging.

 

[Borek]

Lets face it it you had gone to the trouble of sending a probe to Venus you would be able to come up with a better picture than that!

This picture was taken with 1981 technology. If you had better technology at the time, why were you hiding it?

 

[Nik_2213]

IIRC, the later Russian Venus landers had sapphire or diamond windows for their cameras and optical sensors, as anything else would either melt or sag...

If you google for those Venera probes, you'll see how difficult getting *any* data from Venus' surface was...