An interplanetary shock wave hit Earth's magnetic field on Jan. 11th. The impact just after 08:30 UT did not trigger a geomagnetic storm. However, strong magnetic fields downstream of the shockfront opened a crack in Earth's magnetosphere. Solar wind poured in to fuel a nice display of Arctic auroras. The shock wave was not expected. In retrospect, perhaps, it should have been. On Jan. 8th, a huge filament of magnetism launched itself off the surface of the sun. At first the blast did not seem to be Earth-directed. However, yesterday's event may have been a glancing blow from the debris. NASA and European spacecraft have been detecting these cracks for years. Some are as large as California, and sometimes they grow wider than the whole planet. Stay Tuned!