Alex at Worldchanging makes an interesting point about this classic image from space, often used to show how poor and undeveloped Africa is compared to Europe and the USA. But Alex notes that it isn't an image of underdevelopment, it is one of waste.
North America from Space; NASA
Maps of brightness illustrate light pollution and energy waste. The blazing lights our satellites photograph while whizzing above us in their orbits, well, that's light that's serving no useful purpose (unless you want to think of our glowing cities as a form of art meant for distant eyes). Light seen from space is bouncing off illuminated surfaces, or being shone directly from bulbs aimed up. Neither is helping us on the ground see our cities better.
He is absolutely right. Every photon seen from space is electrical energy lost, serving no useful purpose. We sit here worrying about generating more power from nuclear and photocells on every roof but in the meantime, we just throw the stuff away.
Of course we have the technology to fix this; lots of modern, efficient fixtures are designed to aim their light down and not waste it. Lots of good engineers can design lighting systems to distribute it more efficiently. But as we know, efficiency isn't sexy. More in Worldchanging