Blue Flame, Colour photograph (Giclée) by Shane Lamb. Alaskan night sky is dark from August to April. The Aurora is a natural light display caused by charged particles from the sun interacting with the earth's atmosphere. When these particles collide with oxygen, yellows and greens are produced, with nitrogen they produce reds, violets and rarely blues
Shape and abstraction: This image uses negative space perfectly - depending how you interperet it, the negative space can either be the sky because it is less dominant, or the buildings, because they are darker and catch your eye less.
National Geographic's most famous photographs expected to fetch $3MILLION at Christie's in first ever auction of collection
A 1969 illustration entitled A Blue Globe Hanging in the Sky ¿ Earth as seen from the moon by Charles Bittinger will be up for auction at Christie's sale of 'The National Geographic Collection: The Art of Exploration '