The Earth's center is 1,000 degrees hotter than previously thought

[Jim__]

[center][/center]

From phys.org:

Scientists have determined the temperature near the Earth's centre to be 6000 degrees Celsius, 1000 degrees hotter than in a previous experiment run 20 years ago. These measurements confirm geophysical models that the temperature difference between the solid core and the mantle above, must be at least 1500 degrees to explain why the Earth has a magnetic field. The scientists were even able to establish why the earlier experiment had produced a lower temperature figure. The results are published on 26 April 2013 in Science.
...

The Earth's core consists mainly of a sphere of liquid iron at temperatures above 4000 degrees and pressures of more than 1.3 million atmospheres. Under these conditions, iron is as liquid as the water in the oceans. It is only at the very centre of the Earth, where pressure and temperature rise even higher, that the liquid iron solidifies. Analysis of earthquake-triggered seismic waves passing through the Earth, tells us the thickness of the solid and liquid cores, and even how the pressure in the Earth increases with depth. However these waves do not provide information on temperature, which has an important influence on the movement of material within the liquid core and the solid mantle above. Indeed the temperature difference between the mantle and the core is the main driver of large-scale thermal movements, which together with the Earth's rotation, act like a dynamo generating the Earth's magnetic field. The temperature profile through the Earth's interior also underpins geophysical models that explain the creation and intense activity of hot-spot volcanoes like the Hawaiian Islands or La Réunion.

To generate an accurate picture of the temperature profile within the Earth's centre, scientists can look at the melting point of iron at different pressures in the laboratory, using a diamond anvil cell to compress speck-sized samples to pressures of several million atmospheres, and powerful laser beams to heat them to 4000 or even 5000 degrees Celsius."In practice, many experimental challenges have to be met", explains Agnès Dewaele from CEA, "as the iron sample has to be insulated thermally and also must not be allowed to chemically react with its environment. Even if a sample reaches the extreme temperatures and pressures at the centre of the Earth, it will only do so for a matter of seconds. In this short timeframe it is extremely difficult to determine whether it has started to melt or is still solid".

This is where X-rays come into play. "We have developed a new technique where an intense beam of X-rays from the synchrotron can probe a sample and deduce whether it is solid, liquid or partially molten within as little as a second, using a process known diffraction", says Mohamed Mezouar from the ESRF, "and this is short enough to keep temperature and pressure constant, and at the same time avoid any chemical reactions".

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[Thor_MN]

1. Undoubtedly, they stuck the thermometer in at Rush's feet.

If I needed to find the Earth's asshole, that's where I would look.

[Orrex]

2. How long until the Right blames this for global warming?

On the other hand, I love that the graphic looks like an exclamation point?

[rightsideout]

3. Hell is hotter than we thought

[DreamGypsy]

4. Wow, that's cool...the technique and apparatus to make the measurement, that is...

...the temperature is hot. In fact, 6000 C is a bit hotter than the surface temperature of the sun. NASA says 5778 K,
that's 5505 C, for for the effective temperature of the photosphere.

When I searched to verify my recollection about the sun's surface temp I found this interesting article from Scientific American, Ask the Experts, in 1999:

I read that the sun's surface temperature is about 6,000 degrees Celsius but that the corona--the sun's atmosphere--is much hotter, millions of degrees. How does all that energy get into the corona without heating up the surface?

The answer is interesting, though kind of obvious once you know it. Go check it out.

The closing comment from the answer is:

The precise mechanism by which the corona overlying the solar surface is heated to temperatures of one to two million kelvins remains one of the outstanding problems of solar physics. It has long been suspected that turbulent motions in the lower solar atmosphere are propagated outward as waves in some form, which ultimately shock the thin atmosphere above the surface (the photosphere). The shocks thereby dissipate mechanical energy in the waves as heat. When magnetic field lines reconnect, they release energy; some researchers suspect that fine-scale magnetic reconnections above the sun's surface provide the energy to heat the corona.

I'll go look around to see if this problem in 1999 is still unanswered today.

Earth's core is hot. Science is definitely cool.

Thanks for the post, Jim__

[backscatter712]

5. Did I hear right (I slightly remember) that nuclear reactions generate some of Earth's core heat?

I'd have to google like mad to find it, but I seem to remember a science article that suggested that a lot of the heavy elements that existed in Earth's formation sunk to the core - elements like uranium, for example, which turned Earth's core into a nuclear reactor.

[NickB79]

6. Yes, radioactive decay accounts for 80% of the heating

http://en.wikipedia.org/wiki/Geothermal_gradient

The Earth's internal heat comes from a combination of residual heat from planetary accretion (about 20%) and heat produced through radioactive decay (80%).[2] The major heat-producing isotopes in the Earth are potassium-40, uranium-238, uranium-235, and thorium-232.[3]