A string of planes pulls away from the North American East Coast as if being sipped through a straw; they head for Europe. They’re overnight flights to London, Paris, Frankfurt — cities which, at that hour, 11 p.m. (EST), you can’t see on our map. Everybody’s asleep over there. But wait a beat, and with morning Europe turns incandescent; every patch of Britain, France, Italy suddenly buzzes with airplanes.

American astronaut Don Pettit figured out a way to snap still images of nighttime cities, even as the International Space Station was moving at about 17,500 miles per hour. He (and other astronauts) then took high-resolution pictures that show that, from a distance of 250 miles or so, you can still see single highways at night.

Looking down from space, Tokyo glows blue-green. That’s because street lights in Japan are gas discharge lamps that use vaporized mercury to produce light. Blue-green is mercury’s color. So cities up and down Japan twinkle blue-green.

Sao Paolo, Brazil, for example, glows blue-green too, but mainly in one part of town. That’s the older section, built when mercury vapor lights were in vogue. These days, city planners are moving to sodium vapor, which glows slightly orange, so from outer space the colors tell you which part of town is new, and which old.

And check out the image above of Korea and Japan and water in between. The blazing white spots in the middle? Fishing fleets using xenon lights to attract squid.

Via NPR.