Astronauts on board the International Space Station (ISS) take hundreds of night-time pictures each year of cities around the globe. Cities at Night is a “citizen science project that aims to create a map, similar to Google maps, of the Earth at night using night-time color photographs taken by astronauts onboard the ISS.” Check out the photographs that have been geo-referenced to the Earth, or join in and help the project team geo-reference new photographs!