Aurora
To the Inuit of Hudson Bay, the aurora borealis or northern lights were celestial torches that safely guided the dead to the heavenly regions. In medieval Europe, the northern lights were thought by some to be the reflections of heavenly warriors. To the modern scientist, the aurora borealis or aurora polaris of the Arctic and the aurora australis of the Antarctic are less of a mystery. Appearing as luminous -- and sometimes colored -- arcs, rays and bands in the night sky in the high latitudes such as this picture taken from a satellite, luminous auroras occur when the constituents of the upper atmosphere are excited by charged particles from space. While we can see auroras in visible light, auroras also occur in the invisible infrared and ultraviolet regions of the electromagnetic spectrum. The photo was obtained from an informational website about the Aurora Borealis of the Tromsø Museum of Norway. Image courtesy of CERN.

NISE/NSF