Aurora Boreal 4/2000 sobre Göttingen

Fecha: 7.4.2000 Hora: approx. 0 UT Exposición: 2x 30s
Campo visual: 155^o x 70^o Emulsión: Kodak Royal Gold 1000 Filtro: ninguno
Optica: f=17mm, 1/3.5 Lugar: Gross-Schneen, Göttingen Observador: T. Credner & E. Vorlaufer

Fecha:	7.4.2000	Hora:	approx. 0 UT	Exposición:	2x 30s
Campo visual:	155^o x 70^o	Emulsión:	Kodak Royal Gold 1000	Filtro:	ninguno
Optica:	f=17mm, 1/3.5	Lugar:	Gross-Schneen, Göttingen	Observador:	T. Credner & E. Vorlaufer

Shown is a mosaic of two wide angle images giving a 155 degree panorama of the great Aurora display of April 2000. It resembles nicely the overall visual appearance of this event. At lower altitudes (up to 110km) the usual green light of wavelength 557.7 nm by excited oxygen dominates. Above, in the altitude range of 200 - 400 km, the excited oxygen glows red. This red emission can't occur at lower altitude since the atmospheric density is too high. For the red emmission the oxygen needs quite a long time to stay in an excited state. But in the dense lower atmosphere the oxygen looses this energy already by encounters with other particles before the red emission might occur.