STUDY OF METEORS

Evening Post, Volume CXIV, Issue 89, 12 October 1932, Page 7

STUDY OF METEORS

A NEW IMPORTANCE

MIRROR FOR TIMING ,

, When.ithe International \Astronomical •Union met recently at the Massachusetts Institute of Technology, special attention ■was < given, to the rhethods of efficiently attacking observational problems. -■•■•■

Before the commission on meteors, Dr. E. Opik, of Tartu, Estonia.and research associ-1 ate of the Harvard- College Observatory, told how observations in a rapidly wobbling, mirror of th 6 corkscrew-shaped trails of vshooting stars are helping to find, the' speed'o£ these visitors from space. He was introduced by Dr. Harlow Shapley, director of the Harvard Observatory. Dr. Shapley recalled the time when many astronomers thought meteors, which are only observed when they enter- the. earth's atmosphere, hardly worthy of study. He praised Dr. Charles P. Oliver, director of the Flower Observatory of. the University of Pennsylvania and president of the union's commission on meteors, for his pioneer work in this field. But now, he .said, it is realised that meteor study will aid- in the solution of many astronomical problems, particularly of star streaming and the contents of interstellar space. ■ -■■ ■HARVARD'S UNDERTAKING. With this in mind, the Harvard Observatory has undertaken meteor study as a major problem,,and Dr. Opik has, been engaged as one of those mainly responsible for it. A wealth of material is also contaiped in the thousands of photographic plates on file at the Harvard Observatory, and these are being studied for their •records of meteors by Dr. Willard J. .Fisher, of the observatory staff. ■Dr. Opik described the work of the Harvard station for meteor study established, a. year ago near Flagstaff, Ariz, unlike most astronomical observation, this is done without the use of telescopes, but with the aid of special apparatus, one instrument being the wobbling mirror. This is a flat mirror, slightly inclined from the horizontal but mounted to turn around a vertical axis at, a speed of ten revolutions per second. The result is a conical motion.' If a star is observed in it, its image is spread out into an ellipse. 'Since the meteor, or shooting star, is moving -through space, its appearance is a combination of the line and the ellipse, a ,wavy line in the case of a rapidly moving one, or a spiral if the meteor is moving more slowly. Each wave, or turn of the. spiral, indicates a tenth of a second, so by counting them the time taken for the meteor to flash across the sky may be determined. The other fact that must be known about the shoQting star is its path among the stars, and this is obtained by watching the sky through a reticle. This is a framework of -wire held above the head and with the eye in a fixed position. The lines of the reticle correspond to the coordinates on a star map. One eye is used r and when a meteor is observed in the field its path can easily be plotted on the corresponding map. . AMATEUR OBSERVATIONS. . ' Dr. Opik spoke of the value of amateur meteor observations, but said that these are incomplete because they are mostly concentrated on a few nights during the year, and in order to find out the true distribution in space continual observations are necessary. These are being provided by the work in Arizona, in which Cornell University is co-operating. "An hour without a meteor is as important as one with a hundred," he declared. "The number of observations is not important, but the number of hours covered." The meteor section also adopted the text of a resolution decided on at an earlier meeting asking the French Government to undertake an expedition to locate and study a million-ton meteorite reported to be in the Adrar district of the Sahara in North Africa, near the settlement of Chinguetti. It was also voted to send • a similar resolution to the Government of Russia, asking a scientific study of the meteoric mass which fell in Siberia in 1008.