NASA is asking for the public’s help in categorizing hundreds of thousands of night photos of the Earth, most taken from the International Space Station.
The photos are available in an online collection.
People are asked to identify which cities and towns clusters of lights are coming from.
Hundreds of volunteers have already classified nearly 20,000 images, but those need to be confirmed by multiple people.
The main goal is to create an open atlas of nighttime photos of Earth.
The photos will be available to the media, the public and scientists.
In the end, NASA says it could help save energy, contribute to better human health and safety, and improve understanding of atmospheric chemistry.
The Complutense University of Madrid is leading the project.
You can get started at citiesatnight.org.