Featured Research

from universities, journals, and other organizations

To Understand Earth's Magnetic Field, Wisconsin Scientists Study Ball Of Molten Metal

Date:
January 10, 2005
Source:
National Science Foundation
Summary:
In an underground bunker that brushes up against a barnyard on one side and a cornfield on the other, scientists from the University of Wisconsin, Madison, are trying to solve an enduring cosmic mystery: how does the Earth generate its magnetic field—the vast, invisible web that shapes the aurora, makes compass needles point north, and shields us from solar storms?

University of Wisconsin physicist Cary Forest with a prototype of the Madison Dynamo Experiment. In the full experiment, the one-meter wide, stainless steel shell is filled with molten sodium metal. (The prototype used water.) The metal, in turn, is stirred by two motor-driven, opposing propellers so that its motions simulate the natural, magnetic field-generating dynamos inside the Earth's core.
Credit: Jeff Miller

Madison, Wis. -- In an underground bunker that brushes up against a barnyard on one side and a cornfield on the other, scientists from the University of Wisconsin, Madison, are trying to solve an enduring cosmic mystery: how does the Earth generate its magnetic field—the vast, invisible web that shapes the aurora, makes compass needles point north, and shields us from solar storms? And how do similar fields get generated in almost every other planet in our solar system, as well as in the Sun, other stars, and even entire galaxies?

Their tool is the Madison Dynamo Experiment, a newly operational laboratory model of the Earth's molten core. Five years in the making, with support provided jointly by the National Science Foundation (NSF) and the Department of Energy, the experiment is the largest of half a dozen such efforts worldwide. And like all the others, says UW physicist Cary Forest, principal investigator on the project, it is designed to fill in some gaping holes in our understanding.

Theory has it that magnetic fields tend to arise spontaneously in any rotating, electrically conducting fluid, explains Forest, whether that fluid is the molten iron in the Earth's deep interior or the multi-million-degree plasma at the center of the Sun. But empirical evidence is much harder to come by, given that no one has yet figured out how to stick a probe into the core of the Earth, or into the heart of a star.

Thus the gaps. Says Forest, "How fast do the naturally occurring magnetic fields grow? When do they stop growing? What causes them to stop growing? That's the big one. These are really, really fundamental questions that theory doesn't address."

And thus the Madison Dynamo Experiment. At its heart is a one-meter-wide, stainless steel sphere that contains about a ton of sodium metal, which serves as the conducting fluid. Sodium metal is a dull, silvery substance that has the consistency of soft cheese at room temperature, and a dangerous habit of reacting violently with moisture and many other things. But sodium also has the advantage of melting at the comparatively low temperature of 98 degrees centigrade, or 208 degrees Fahrenheit, above which it flows like water. (Iron, by contrast, doesn’t melt until 1538 degrees centigrade, or 2800 degrees Fahrenheit.)

When the experiment is in operation, two opposing propellers stir the molten sodium in ways that approximate the flow of molten iron inside the Earth.

"At the core of the Earth, it is thought that there are lots of little flows and swirls occurring that contribute to the generation of the planet's magnetic field," says Forest. But "it's the details that are important, and with the Madison Dynamo Experiment we can turn the knobs and see what happens."

Indeed, says Forest, with the Madison Dynamo Experiment now operational and generating data, the secrets of how natural dynamos perform will begin to emerge and the limits of current theory can begin to be tested.


Story Source:

The above story is based on materials provided by National Science Foundation. Note: Materials may be edited for content and length.


Cite This Page:

National Science Foundation. "To Understand Earth's Magnetic Field, Wisconsin Scientists Study Ball Of Molten Metal." ScienceDaily. ScienceDaily, 10 January 2005. <www.sciencedaily.com/releases/2005/01/050106090451.htm>.
National Science Foundation. (2005, January 10). To Understand Earth's Magnetic Field, Wisconsin Scientists Study Ball Of Molten Metal. ScienceDaily. Retrieved September 18, 2014 from www.sciencedaily.com/releases/2005/01/050106090451.htm
National Science Foundation. "To Understand Earth's Magnetic Field, Wisconsin Scientists Study Ball Of Molten Metal." ScienceDaily. www.sciencedaily.com/releases/2005/01/050106090451.htm (accessed September 18, 2014).

Share This



More Earth & Climate News

Thursday, September 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Scientists Examine Colossal Squid

Raw: Scientists Examine Colossal Squid

AP (Sep. 16, 2014) Squid experts in New Zealand thawed and examined an unusual catch on Tuesday: a colossal squid. It was captured in Antarctica's remote Ross Sea in December last year and has been frozen for eight months. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Man Floats for 31 Hours in Gulf Waters

Man Floats for 31 Hours in Gulf Waters

AP (Sep. 16, 2014) A Texas man is lucky to be alive after he and three others floated for more than a day in the Gulf of Mexico when their boat sank during a fishing trip. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Researchers Explore Shipwrecks Off Calif. Coast

Researchers Explore Shipwrecks Off Calif. Coast

AP (Sep. 16, 2014) Federal researchers are exploring more than a dozen underwater sites where they believe ships sank in the treacherous waters west of San Francisco in the decades following the Gold Rush. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Isolated N. Korea Asks For International Help With Volcano

Isolated N. Korea Asks For International Help With Volcano

Newsy (Sep. 16, 2014) Mount Paektu volcano in North Korea is showing signs of life and there's not much known about it. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins