The golden hour is the period of time (roughly an hour) immediately either side of sunrise/sunset. At this time the sun is very low in the sky. As a result the light passes through much more of the atmosphere. The result of this is that:

• the high frequencies (blues) are filtered out giving a very warm light

• the light is diffused by particles in the air, softening the light for softer shadows

• the lighting angle is very low which gives great sculpting light, and long shadows

• the intensity of direct sunlight is much reduced, allowing you to shoot into the sun without silhouetting.

All of this means you can grab images like this. The reduced intensity of the direct sunlight means the light from the rest of the sky is brighter by comparison, this provides a great soft fill in light, allowing the direct sunlight to be used as a back/rim light to accent shapes.

The term "golden" partially refers to the warm colour of the light, and partially to the fact that everything you shoot turns to gold during the golden hour!