A giant breach in Earth's magnetic field

NASA's five THEMIS spacecraft have discovered a breach in Earth's magnetic field ten times larger than anything previously thought to exist.

Solar wind can flow in through the opening to "load up" the magnetosphere for powerful geomagnetic storms. But the breach itself is not the biggest surprise. Researchers are even more amazed at the strange and unexpected way it forms, overturning long-held ideas of space physics.

Read the full NASA story at
http://science.nasa.gov/headlines/y2008/
16dec_giantbreach.htm