As Earth sleeps, lights pulse across its surface in an animated dance visible from space. This beautiful composite of satellite images of cloudless nights collected over a period of one year. A quick glance reveals the obvious: Wealthy, developed regions, such as the United States, Europe, and Japan, are lighting up with garish abandon, using energy disproportionate to their populations. In the coming decades, many scientists expect more lights in developing countries. But some expect fewer lights in wealthier nations, where advances in lighting technology could save energy and better contain light emissions. Published in November 2004, this map is one half of a two-map set featuring a political map of the world.