Oxygen Red Emission

During some of the phases of the aurora on April 7, 2000 the whole sky, from the northern horizon to the zenith, was of an intense red color (spectral line of oxygen 630.0nm). This can be seen in the picture on the left which shows the sky from the altitude of about 15░ above the horizon to about 80░. However, the aurora's emission in the green line of the oxygen (557.7nm) is present to. Evidence of this can be made by extracting the green component from the color picture and then increasing its contrast. We will obtain a black-and-white picture (on the right) which clearly shows the green emission of the aurora. When viewed with the naked eye it was hardly visible and had a yellowish tinge. The yellow color was created by combining the green and red monochromatic light.

After about half an hour the red emission faded away while the green one at wavelength 557.7nm increased, as you can see on the following picture.