While a pink sky at night might be a shepherd's delight, London residents were left scratching their heads early this morning as a mysterious pink cloud drifted over the city. Bemused bystanders in Mayfair craned their necks to witness the strange light that appeared for just under an hour. A cloud is usually made up of a visible mass of droplets or frozen crystals floating in the atmosphere above the surface of the Earth or another planetary body. Pink clouds occur almost entirely at sunrise and sunset and are the result of the scattering of sunlight by the atmosphere. The clouds themselves are not pink - they reflect rays of sunlight which are predominant at that time.But this atmospheric phenomenon is so far unexplained.
There has been some speculation that it is a promotion by Breast Cancer Awareness, which is associated with the colour pink.
Or maybe, with UFOs once again hitting the headlines this week, it is the vapour trail from an alien spacecraft.