The GLOBE at Night (GaN) program, hosted by the U.S. National Optical Astronomy Observatory (NOAO), is an international citizen-science campaign to raise public awareness of the impact of light pollution. The worldwide campaign invites citizen-scientists to record the brightness of the night sky by visually matching the appearance of a constellation like Orion with star maps of progressively fainter stars or using meters to obtain more precise measurements. Measurements are submitted to a central website by computer or smart phone. From these data an interactive map of all worldwide observations is created.

Gan 2013 postcarddates

Every year, NOAO is adding more opportunities for participation by providing campaigns at different times of year and creating Web applications in different languages for smart phones. Over the past 7 years of 10-day campaigns, people in 115 countries have contributed over 83,000 measurements, making GLOBE at Night the most successful, light pollution citizen-science campaign to date. There are 5 GLOBE at Night campaigns in 2013: January 3 - 12, January 31 - February 9, March 3 - 12, 2013, March 31 - April 9, and April 29 - May 8. (See for more information.)