All images have been taken by astronauts from NASA, CSA-ASC, ESA, ROSCOSMOS and JAXA. You can find the original pictures on the website “Gateway to astronaut photography of Earth”:
The Cities at Night website content was developed entirely to be used for outreach and scientific research. Its content and all derived products created as result of Cities at Night project activities can be used for those purposes as long as the following citation of the project is included:
Creative Commons License. Cities at Night by Alejandro Sánchez de Miguel et al. Atlas of astronaut photos of Earth at night A&G (2014) is distributed under Creative Commons Non commercial attribution – Share 4.0 International licence.
However, if the Cities at Night data are a principal component of a science paper then co-authorship to PI’s should be offered.