What is Cities at Night?
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 colour photographs taken by astronauts onboard the ISS.
When visiting Paris for the weekend, one easily takes over 300 tourist pictures; imagine how many you would take if you were out in space. That is exactly what happens to the astronauts out in space. They easily take hundreds of photographs of earth and although some of those contain carefully selected frames, focus and exposure, many of the pictures are taken automatically so that the astronauts can continue working on their experiments.
NASA has a database with almost half a million pictures taken by the astronauts on the International Space Station.To organise all this data with the use of computers would be infeasible since it would take extremely complex algorithms to interpret the photographs.
The human eye, however, knows immediately if the camera was pointing at a city or simply at the stars. For this reason we created Cities at Night, a platform with different apps with which anyone can help while enjoying beautiful pictures taken from space.
Lost at Night
Lost at Night is our current working app. Help recogniting cities from several given options.
Currently, the best available map of the earth at night is the Black Marble Map. It was created with data from the Suomi NPP Satellite using the VIIRS (Visible Infrared Imaging Radiometer Suite) camera. The images used to build the map, have a scale of about 750 metres per pixel. The map has been made entirely with black and white photography. The colours that you see in the black marble map are not real; instead they are an artistic manipulation.
With the Cities at Night project we are building a map of the earth at night entirely in real colour for the first time. Furthermore, we are using pictures with up to 150 times more resolution than the images used to build the Black Marble Map. Depending on the type of lens, the ISS images used by Cities at Night can reach a resolution of up to 5 metres per pixel, which is a significant improvement from the VIIRS images with a resolution of approximately 750 metres per pixel.
Both the Black Marble Map and the Cities at Night Map help us locate the best stargazing places. And even more importantly, both maps can help us detect excessive amounts as well as inefficient types of light; making these maps an important tool in protecting our planet from harmful light pollution.
Space agencies words
Cities at night has the collaboration of the Spanish Foundation for Science and Technology (FECYT) – Ministry of Science and Innovation, through its 2018 call for grants for the development of scientific, technological and innovation culture.