At sunrise and sunset, we see the sun through a greater thickness of air because it is low in the sky. Therefore, we are looking at it across the earth’s surface rather than directly up into the sky. At these times, the sky often turns orange-red because the photons of red and orange light are scattered through the atmosphere around us. As the sun sets or rises, its light travels to us across the Earth’s surface. The colours of the spectrum are gradually scattered. Red and orange are the last to be scattered before the sun finally sets or rises.