Cool Geo-Video: Earth's Magnetic Field

Cool Geo-Video: Earth's Magnetic field - another great post from NASA's Earth Observatory. I particularly like the visualization of the wandering magnetic north in the video link.

Source: NASA's Earth Observatory 
Quick "Cut & Paste" Summary:

"....Launched in November 2013 by the European Space Agency (ESA), the three-satellite Swarm constellation is providing new insights into the workings of Earth’s global magnetic field. Generated by the motion of molten iron in Earth’s core, the magnetic field protects our planet from cosmic radiation and from the charged particles emitted by our Sun. It also provides the basis for navigation with a compass...."

" ....Geophysicists have noted that the strength of Earth’s magnetic field has been decaying—about 5 percent globally over the past century. However, it is not changing in a uniform way; it grows growing stronger in some places and weaker in others. ...."

"....[t]he changes are a natural variation due to processes in the deep interior of the Earth ....[t] he movement of molten iron in the core creates electric currents, and electric currents create a magnetic field. So every change in the flow of the core means changes in the magnetic field...."

Credits & References: 

1. European Space Agency (2014, June 19) Swarm Reveals Earth’s Changing Magnetism. Accessed September 5, 2014.
2. NASA Earth Observatory (2011, April 23) Earth’s Magnetosphere.
3. NASA Earth Observatory (2004, May 22) Earth’s Surface Magnetism.
4. NASA Earth Observatory (2004, March 30) Gravity Recovery and Climate Experiment.

Images and video courtesy of European Space Agency/Technical University of Denmark (ESA/DTU Space). Caption by Mike Carlowicz, based in part on a story from the European Space Agency.