City lights broadcast our existence into the night of space. Imagine how the Earth will look to astronauts in a century's time or longer? These images are incredibly difficult to take from a spacecraft traveling along at almost 28,000 kilometers per hour. The images are held at NASA's Johnson Space Center in a special archive for astronaut photography. Watch for the great cities of Beijing, Istanbul, Melbourne, Montreal, London, San Francisco, Los Angeles, Las Vegas, Buenos Aires, Brasilia (one of our favorites), and more.