What is Cities at Night?



Cities at Night is a citizen science project that aims to create a map of the earth at night in the style of Google maps using nighttime photographs taken by astronauts onboard the ISS.

When visiting Paris for the weekend, you easily take over 300 tourist pictures, imagine how many you would take if you were in space.That´s 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.

sample-img11NASA 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 3 apps with which anyone can help while enjoying beautiful pictures taken from space.


The Game. NightKnights.eu

We are testing the new game that will help us with the map. Code by Cefriel Night Knights makes you play with a partner while sorting out pictures. Get points when you both agree on the classification and download the pictures you like the most directly from NASA servers.



Play night knights

Have you tried the 3 apps?

Help classify pictures astronauts took from the ISS




Dark Skies



With this application you can help identify the city shown in the picture.




Lost at Night




With this application you can help georeference a picture so it will appear in the right place and position on the map.




Lost at Night





Building the map


Currently, the best map of 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 colours that you see in the black marble map are an artistic manipulation because in reality the map is entirely created with black and white photographs.

  •  Bluemarbel 

    With Cities at Night we are building a map of the earth at night entirely in colour. 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 lens used, 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.

    Google engine

    More maps

  • Both the Black Marble Map and the Cities at Night map help us locate the best stargazing places as well as places with an excessive amount of light. Making the maps an important tool in protecting our planet from harmful light pollution.



    Scientific research documentation 


    Space agencies words 



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    ESA Italia


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    ESA España


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    Our Partners 

    • Stars4all
    • UCM
    • IAA
    • CEGEP
    • ESA
    • Gateway
    • Google
    • Crodcrafting