Pink auroras
© Markus Varik
Surprising forecasters, 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.

"I was running around my apartment like a maniac, looking for pants and camera equipment," says photographer Markus Varik of Tromsø, Norway. " I didn't have enough time to go to completely dark location--but I didn't need to. The auroras were so bright."

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: movie. At first the blast did not seem to be Earth-directed. However, yesterday's event may have been a glancing blow from the debris.