'Orbit' takes the reader into space for astronaut's views of home - Cape Cod arching into the Atlantic, Mount Everest casting its shadow over lesser peaks, the sands of the Sahara arrayed in endless patterns. Like any travelers, these voyagers in space have aimed their cameras at sights that startled their eyes. They have flown through the aurora and captured its rippling, mystic colors. They have looked down upon storms and volcanoes. And they have documented the human imprint upon the Earth - the scarred forests, the topsoil washing into the sea. As these matchless photos show, we now keep a vigil over our Earth, a vigil that will help us preserve this realm of fragile beauty.