At a few hundred kilometers altitude, the Earth fills half your sky, and the band of blue that stretches from Mindanao to Bombay, which your eye encompasses in a single glance, can break your heart with its beauty. Home, you think. Home. This is my world. This is where I come from. Everyone I know, everyone I ever heard of, grew up down there, under that relentless and exquisite blue.
You race eastward from horizon to horizon, from dawn to dawn, circling the planet in an hour and a half. After a while, you get to know it, you study its idiosyncrasies and anomalies. You can see so much with the naked eye. Florida will soon be in view again. Has that tropical storm system you saw last orbit, swirling and racing over the Caribbean, reached Fort Lauderdale? Are there any of the mountains in the Hindu Kush snow-free this summer? You tend to admire the aquamarine reefs in the Coral Sea. You look at the West Antarctic Ice Pack and wonder whether its collapse could really inundate all the coastal cities on the planet.
In the daylight, though, it's hard to see any sign of human habitation. But at night, except for the polar aurora, everything you see is due to humans, humming and blinking all over the planet. That swath of light is eastern North America, continuous from Boston to Washington, a megalopolis in fact if not in name. Over there is the burn off of natural gas in Libya. The dazzling lights of the Japanese shrimp fishing fleet have moved toward the South China Sea. On every orbit, the Earth tells you new stories. You can see a volcanic eruption in Kamchatka, a Saharan sandstorm approaching Brazil, unseasonably frigid weather in New Zealand. You get to thinking of the Earth as an organism, a living thing. You get to worry about it, care for it, wish it well. National boundaries are as invisible as meridians of longitude, or the Tropics of Cancer and Capricorn. The boundaries are arbitrary. The planet is real.
from Contact, by Carl Sagan, 1985