An oceanic expanse of pre-dawn gray white below obscures a checkered grid of Saskatchewan, a snow plain nicked by the dark, unruly lines of woody swales. One might imagine that little is to be seen from a plane at night, but above the clouds the Milky Way is a dense, blazing arch. A full moon often lights the planet freshly, and patterns of human culture, artificially lit, are striking in ways not visible in daylight. One evening I saw the distinctive glows of cities around Delhi diffused like spiral galaxies in a continuous deck of stratus clouds far below us. In Algeria and on the Asian steppes, wind-whipped pennants of gas flared. The jungle burned in incandescent spots in Malaysia and Brazil. One clear evening at 20,000 feet over Manhattan, I could see, it seemed, every streetlight halfway to the end of Long Island. A summer lightning bolt unexpectedly revealed thousands of bright dots on the ink-black veld of the northern Transvaal: sheep.