August 20, 2008
The pair of the full sky photos above shows the evolution of an auroral substorm above northern Finland on March 2004. At left is shown an extremely dynamic auroral display, which was observed from northern Finland on March 14, 2004 at 2:29 a.m. The observed auroral arcs and structures depicted here were moving and changing almost fluid-like. Click on images for a larger view.
The display at right features a pulsating aurora, a type of aurora which fills parts of the sky with pale light patches appearing and disappearing independently of each other on a time scale of few seconds. This image was taken on March 14, 2004 at 3:28 a.m. While the visual impression is quite stunning to those who witness these displays, pulsating aurorae are rather hard to photograph due to their relative dimness and brief appearance.