May 06, 2002
These 2 images of northern Egypt, taken by the DMSP visible sensor on September 28, 1995, show the difference between day and night on the Nile delta. In contrast to the bright desert landscape (the barren desert reflects light in the visible wavelengths), the fertile Nile delta and Nile River valley are dark (light is more readily absorbed) on this black and white image. The delta and river valley are where most of Egypt's approximately 60 million inhabitants live and also where most of the food is grown. On the nighttime image, the Nile River and delta looks like a funnel of light. A photomultiplier sensing device is used for nighttime imaging on the DMSP satellite. The city of Cairo (nearly 7 million people) blazes at the base of the Nile delta, and the city of Alexandria is the luminous strip at the upper left of the delta. To the west of Cairo, the bright "islands of light" are gas flares (excess natural gas is being burned) associated with Egypt's oil fields. Note that the Mediterranean Sea is at top (north), and the Red Sea is to the east (right).