National Geographic : 1965 Nov
30 times farther than earth from the sun, and possibly to Pluto, 40 times farther than earth. Modern eclipse expeditions took on a new look in 1958, when scientists first attempted to use rocket astronomy to determine which layers of the solar atmosphere emit X-rays and ultraviolet. The expedition was a joint venture of ground-based astronomers, under the leadership of Dr. John W. Evans of the Sacramento Peak Observatory in New Mexico, and a team of rocket specialists from the U. S. Naval Research Labora tory, under my direction. The eclipse began at sunrise on the equator near New Guinea and raced across the Pacific Ocean for about 8,500 miles to the coast of Chile near Val paraiso, where it left the earth at sunset. In its long path-never more than 150 miles wide-the eclipse missed all the large South Pacific islands, and could be observed on land from only a few coral atolls. Rocket Barrage Takes Solar Pulse The astronomers chose the atoll Puka Puka in the Danger Islands-about 2,300 miles south of Honolulu-on which to set up their spectrographs. To support the rocket part of the expedi tion, the Navy provided a floating hotel, machine shop, and laboratory-a land ing ship called the Point Defiance. Our six solid-fuel rockets, 1,500 pound combinations of Nike-booster first stages and Asp second stages, point ed like arrows from the deck. The Asp second stages would enter the eclipse shadow about 100 miles up, reach a peak of 150 miles, and splash into the sea 60 miles astern about six minutes after firing. Eclipse day dawned gray and over cast where the Point Defiance lay to, 30 miles off Puka Puka. At 8:38 we fired the first rocket, 10 minutes before totali ty. Two more were fired during the brief interval of totality. Sixteen minutes later No. 4 flashed into the sky. Rocket No. 5 balked, but the sixth rocket took off almost on schedule. When the smoke had cleared, our thoughts shifted to our colleagues on Puka Puka. The sad story that we picked up shortly after on the radio told of rain and clouds that completely ruined their 737 Birth and death of the solar system EVENTEENTH-CENTURY MAN found it easy to vis ualize the end of the world in flames from a passing comet, as shown in the engraving above. Today's scien tists foresee a much different finale, as shown in Davis Meltzer's composite painting on the next two pages. Per haps five billion years hence, they suggest, the sun will exhaust its hydrogen fuel and flare into a "red giant" star that will engulf the nearer planets. The painting shows five stages in the life cycle of the solar system. Some five billion years ago, a dark super cloud of cosmic dust and gas, including debris of a giant exploded star, roiled like a turbulent thunderhead in the Milky Way (top). Gravity contracted the cloud; contraction accelerated its rotary motion. It flattened like a fried egg (stage 2). As contraction continued and the protostar grew hotter, hydrogen atoms collided with increasing violence. They began to fuse, and the sun's thermonuclear furnace was ignited. Meanwhile, fringes of the cloud disk condensed into blobs of dust and gas-the planets (stage 3). The planets cooled; the sun's heat balanced its gravity to halt contraction; and the solar system began to spin sedately as we know it today (stage 4). Finally, billions of years in the future (foreground), the solar reactor will devour its remaining hydrogen and swell into the red giant that swallows up and vaporizes earth. PAINTING (FOLLOWING PAGES) PRODUCEDBY NATIONAL GEOGRAPHICSOCIETY, DAVIS MELTZER,ARTIST © N.G.S .