Until recently , night images taken from 17,500-mph space station could be blurry . Now they are clear and sharp as a razor blade. University in Madrid broke images down into three categories with different aims . Satellites collect data more regularly , but the photos tend to be lower resolution . `` Now the pictures are clear , but their location may not be , which limits their usefulness . Researcher : Madrid brighter than Berlin , despite economic disparity between cities .
Until recently , night images taken from 17,500-mph space station could be blurry . Now they are clear and sharp as a razor blade. University in Madrid broke images down into three categories with different aims . Researcher : Madrid brighter than Berlin , despite economic disparity between cities .