He told the Mail Online: 'the "phenomenon" has the same greenish colour as the Northern Lights. That means the Northern Lights is the source of light causing the strange phenomenon.'

It is an important term in photography to denote the quality of a light source. Sources rich in red light have a low colour temperature and sources rich in blue light have a high colour temperature.

In this paper we have discussed the relation between the whiteness of the light source and lightness, achromatic stimulus sensation and colour temperature etc.