These photos were taken by the Visible Infrared Imaging Radiometer Suite (VIIRS) on a satellite called Suomi-NPP. This satellite orbits at 824 km (512 miles) above the Earth in a polar orbit, traveling north/south/north, etc. Suomi-NPP completes one orbit every 98 minutes and collects one strip of imagery each orbit. Over the course of a day it photographs the entire planet. You can see each orbit's strip of images by looking for the lighter streaks (the Sun's reflection), overlapping images, and/or missing blocks of data.
You can see where this satellite is right now on the Suomi-NPP orbit tracker.