National Geographic : 1970 Aug
21JUPITER EKTACHROME(ABOVE)BYLUNARANDPLANETARYLABORATORY, UNIVERSITYOF ARIZONA;PAINTINGBY LUDEKPESEK© N.G.S. Tumultuous cloud currents sweep Jupiter and eddy around the Great Red Spot in a revealing 1966 photograph. Bulging equator reflects the planet's rapid rotation, once every 9 hours and 55 minutes. Jupiter's turbulent atmospheric bands, com posed largely of frozen and liquid ammonia compounds, kaleidoscopically change shapes and colors; they swirl above a stormy interior of mounting pressure, perhaps crackling with light ning. Deep inside, at a level no instrument can detect from Earth, the planet's substance is crushed into a solid core of hydrogen. Baring its woundlike brand, a crescent Jupiter overwhelms its snowy satellite Amalthea, fore ground, only 70,000 miles away. The Great Red Spot, weirdly vivid in this portrayal, puzzlingly waxes and wanes, all the while drifting across the southern hemisphere. Monstrous Jupiter, a quarter-million miles around, has one and a half times the volume of all the other planets combined. Its satellite Gany mede equals Mercury in size. Jupiter seems in some ways to be less a planet than a star, or rather, a potential star whose nu clear furnace never lighted. Like the sun and oth er stars, it gives off more energy than it receives, while around it swirl a dozen satellites-its own planetary system. Jupiter's atmosphere contains ammonia and methane, gases that wrapped the primordial Earth billions of years ago, when life began. Thus Jupiter could offer a natural laboratory for view ing chemical reactions that might launch life.