Ashen light

Ashen light is a hypothesised subtle glow that has been claimed to be seen on the night side of the planet Venus. Perhaps the ashen light is an analogue of the glow of the Earth's atmosphere. The phenomenon has not been scientifically confirmed, and theories as to the observed phenomenon's cause are numerous, such as the emission of light by Venus, or optical phenomena within the observing telescope itself. A modern hypothesis as to the source of light on Venus suggests it be associated with lightning, for which there is some evidence on Venus. This theory has however fallen out of favour, as there is not enough light generated by this lightning so as to be observed. A more recent hypothesis is that it is a form of transient aurorae or airglow caused by unusually high solar activity interacting with the upper Venusian atmosphere.