The sky plays a critical role in sustaining life on Earth, providing a medium for the transfer of heat and energy. The availability of daylight in the sky is affected by various factors such as latitude, altitude, time of day, time of year, atmospheric conditions (e.g. air pollution) and weather conditions. In our imagination and everyday perception, the sky is the “home” of the sun, and its changing colours play a large part in shaping our aesthetic and emotional experience of daylight.