The NASA/NOAA Suomi NPP satellite's day/night band measures light emanating from the ground showing human settlements and industrial activity, and also moonlight reflected off of clouds. The image on the left was taken on October 21, 2012, an evening of a waxing crescent moon with little cloud cover over the northeastern US. The image on the right was taken in the early morning of October 31, 2012, a day after a full moon. The clouds are the remnants of Hurricane Sandy with just a few openings in the clouds showing the lights, or lack of them, from northern New Jersey and New York City.