National Geographic : 1963 Nov
ROBERT OAKES, NATIONALGEOGRAPHIC LIAS Inverted crescents of the eclipsed sun pattern the chest of John Oakes in Falls Church, Virginia, where the moon hid 82 percent of the solar disk. Openings among the leaves of a tree acted as lenses, producing the pinhole-camera effect. from the enveloping night experienced by eclipse observers on the ground. Suddenly the blast of a whistle shrilled in our ears. It was the agreed signal by which Dr. Deutsch, perched with his filter binocu lars at a window amidships, announced the sighting of Baily's beads. They marked the beginning of totality, the moment when the sun's last rays, glinting through canyons on the moon's rim, appeared as beadlike spots of light. The whistle, incidentally, had been borrowed from a Canadian Mountie at the Edmonton airport. During totality, camera shutters clicked, image converters flashed, motion-picture cam eras and tape recorders purred. Many of us were too busy tending instruments to watch the sky's most awesome spectacle unfold. The sun's corona, not visible except during eclipse, spread its pearly halo and glowed against the sky's dark steel blue. Stars ap peared near the blacked-out sun. Venus gleamed in the darkened heavens (page 789). At the edge of the black disk we could see solar prominences-jets of gas that sometimes erupt from the sun at speeds of 250 miles a sec 796 ond and to heights of 250,000 miles or more. A second whistle from Dr. Deutsch signaled the reappearance of Baily's beads as the sun's limb (outer edge) emerged from behind the moon's retreating rim. Our time in totality had lasted 142 seconds compared with a possible 144. For eight minutes more we continued along our autopilot-controlled great-circle course while some experiments still went on. Then tension relaxed. Grins appeared as men broke out lunches. An hour and 20 minutes later we landed at Edmonton for refueling. A New Approach to Astronomy The three-and-a -half-hour return flight to Long Beach that same evening gave us an opportunity to assess preliminary results. While not all the observers achieved all their goals, Dr. W. N. Arnquist, project manager, said: "Operationally, the expedition was a gratifying success." The successes include physicist Kissell's data on infrared radiation in ranges never before recorded, data that may open new knowledge about the sun's upper atmosphere. Our Douglas spectrograph obtained a rich record of a section of the corona extending out from the limb for a million miles; analysis could reveal valuable information about this gaseous envelope. But months of study must precede final evaluation of APEQS results. Still, far-reaching conclusions can already be drawn, conclusions that point to a new era in astronomical observation. Our expedition demonstrated that a large jet transport can serve admirably as a stable platform high in the air-a stratospheric observatory. Our au topilot kept our wingtips level with no more deviation than one-fourth of a degree during the critical period, and our longitudinal pitch ing was even less. However, as Dr. Deutsch enthusiastically remarked, much credit must be reserved for the able airmanship of the flight crew. The leading edge of the moon's shadow was inter cepted practically on dead center within three seconds of the moment planned. With an airplane navigated and stabilized to this accuracy, the National Geographic Douglas Aircraft APEQS Expedition pio neered techniques that could become stand ard procedures for future experiments. "In such an observatory," Dr. Righini pre dicts, "astronomers could conveniently con duct many valuable experiments from the stratosphere in addition to those concerning eclipses of the sun."