Earth at Night, geographic distribution of cities, NASA. 地球夜晚, 城市的地理分佈

Earth at Night | NASA
http://www.nasa.gov/image-feature/south-africa-from-the-space-stations-earthkam

Daily Wallpaper: Earth at Night | I Like To Waste My Time
http://iliketowastemytime.com/2015/09/16/daily-wallpaper-earth-night