These images were taken by the Suomi National Polar-orbiting Partnership, a satellite run jointly, as the name suggests, by NASA and the NOAA. In these shots, the satellite is using a Visible-Infrared Imager/Radiometer Suite, or VIIRS, to see the difference between vegetation-rich and arid land. It bounces beams off Earth and detects changes in its reflection, allowing it to see vegetation, since vegetation reflects infrared and near-infrared light in a different way than other materials. But it's even more useful than that; VIIRS is used to monitor not just the existence of vegetation, but how it changes and expands and contracts over time.