Earth's Core Made In Miniature

ananyo writes "A 3-meter-tall metal sphere full of molten sodium is about to start work modeling the Earth's core. The gigantic dynamo, which has taken researchers ten years to build, 'will generate a self-sustaining electromagnetic field that can be poked, prodded and coaxed for clues about Earth's dynamo, which is generated by the movement of liquid iron in the outer core.'"

Re:How they know...

[sslayer]

Do you know what happens with practice and theory? In theory, they are both the same. In practice, they are not.

Re:That doesn't sound right...

[Megahard]

Well, you could check. Melting point of sodium is 97.72 C.

Re:That doesn't sound right...

[Baloroth]

Sodium != salt, which is probably what you are thinking of (seems to be the trend in the comments around yours). Sodium is a metal, not a salt (NaCl is common table salt, which melts closer to 1000C or something).

Re:Just starting?

[schiiz]

The experiment was previously filled with water in order to resolve the fluid flow. Water and Sodium have very similar viscous properties so long as you have the temperatures correct. Sodium is also opaque so you can't use lasers and are limited to a combination of ultrasound and flow tomography (basically, backing out the flow from the induced magnetic field), so its somewhat common practice to do a water model of sodium experiments. Lathrop's Water part of the experiment lasted 4ish years? (I think, perhaps between 2 and 4?) because he encountered some interesting hydrodynamic effects. I saw Dr. Lathrop speak at a conference about 3 weeks ago and they were about halfway thru the fill process then, so this article lines up quite nicely with what would have been a reasonable completion time.