||Urban centres create a bubble of light overhead, known as sky glow. Sky glow is a form of wasted energy and light pollution that reduces our view of the night sky, contributes to the destruction of wildlife habitat, and impacts human health. There are many sources that contribute to sky glow: light from residential and business windows, illuminated signs, uplight on buildings and billboard advertizing, and street illumination. An aerial view of a city at night suggests that street lighting is a major contributor to sky glow. In this note we quantify the percentage contribution of street lighting to sky glow, over the city of Reykjavik (Iceland).