The light pollution map has two base layers (road and hybrid Bing maps), VIIRS/World Atlas/Clouds/Aurora overlays and a point feature overlay (SQM, SQC and Observatories). If you want detailed analysis of radiance (VIIRS/DMSP) changes over a period of time, then please use the Lighttrends web application (not mobile optimised). For more information view the help. Send comments about the app and re