NASA's THEMIS spacecraft recently discovered a giant breach in Earth's magnetic field, and as a result, we may be in for more powerful geomagnetic storms. Additionally, researchers were surprised at the way the breach was formed. For more, see this article(1)/video(2) from NASA.

1. http://science.nasa.gov/headlines/y2008/16dec_giantbreach.htm
2. http://www.nasa.gov/mpg/297403main_THEMIS_svsLG.mpg