  We present the results of the analysis of satellite imagery to study light
pollution in Spain. Both calibrated and non-calibrated DMSP-OLS images were
used. We describe the method to scale the non-calibrated DMSP-OLS images which
allows us to use differential photometry techniques in order to study the
evolution of the light pollution. Population data and DMSP-OLS satellite
calibrated images for the year 2006 were compared to test the reliability of
official statistics in public lighting consumption. We found a relationship
between the population and the energy consumption which is valid for several
regions. Finally the true evolution of the electricity consumption for street
lighting in Spain from 1992 to 2010 was derived, it have been doubled in the
last 18 years in most of the provinces.
