Unless they are astronauts, humans must view the universe through the window of the Earth’s atmosphere. Although a clear sky is relatively transparent to visible light, bright astronomical objects — most noticeably the Sun — can paint the entire sky with luminosity, colour and shadow, to be captured by both landscape painters and photographers. How does this happen and what physical processes are responsible for these beautiful colours, gradations and patterns? In this recording of a live online talk, Dr Bob Fosbury explains some of this and illustrates his points with spectacular images of the sky from space and from above the European observatories in the Chilean Atacama desert.

Dr Robert (Bob) Fosbury is emeritus astronomer at the European Southern Observatory and an honorary professor at the Institute of Ophthalmology at UCL.