Black aurora near Tromsø
This video clip shows real-time video of the sky above the EISCAT radar facility near Tromsø, Norway, with a field of view of about 30 degrees and no filters. In addition to the black auroras seen at about 100 km altitude, the background star field and passing satellites can be seen as stationary and moving white dots, respectively. The two orthogonal arrows near the top-left of the image give reference directions and amplitude scale for the arrow in the middle of the image, which shows the direction and speed of the horizontal plasma flow in the ionosphere at about 250 km altitude taken from EISCAT radar tri-static observations. The purpose of this experiment was to determine whether ionospheric plasma flow correlated to the motion of the black auroras. It does not, leading to the conclusion that the motion of the black auroras is controlled by an unknown mechanism in the magnetosphere.
Credit: Video courtesy of Michael Kosch.