The International Geophysical Year

Abstract

rpHE International Geophysical Year 1957-58 will be written into JL history books because it recounts how man made his break through to study of space beyond atmosphere of his own planet Earth. But first a word of history itself. Early man could not but be aware of sun and moon. Indeed, we know that Egyptians among others derived their calendar from observing first moon, then sun. It was important in producing food that they should be able to predict seasons, especially when Nile was likely to overflow and bring life-giving water to crops. Temples were built to sun and it was recognized for what it is, source of heat, light and life as we know it on this planet. Throughout, sun has been and still is predominant character in our story. Besides sun, moon and stars, early man must also have been aware of other natural phenomena such as thunder and lightning and unpredictable variability of weather, and those who lived in northern and southern parts of world would be aware of northern lights and southern lights which appeared in sky from time to time. The name for northern lights, aurora borealis, was first used by Gassendi in 1621 and aurora australis for southern lights seems to have been initiated by Captain James Cook when he saw them in 1773 at lat. 570 8' S. There are records of observations going back a long way. Aristotle in about 350 b.c. mentions aurora and Seneca (a.d. 5-65) refers to aurora in 'Questiones Naturales' as the fiery recess in sky like a cave dug out of space. Man being of a curious habit of mind wants to find an explanation for such natural phenomena. Although some of Greek philosophers believed that world was a globe they did not know how it moved in relation to sun. Copernicus, Galileo, Kepler, Newton, and others three or four hundred years ago, by application of their genius discerned a pattern in movement of heavenly bodies and gave us laws of their motions. The sun and not earth was centre of system of which man's planet was but a part. The sun's or solar system is but a part of an immensely greater whole which is Universe. Let us look briefly at some of earlier studies of earth itself. Queen Elizabeth's physician, William Gilbert (1540-1603), in 1600 published a book called 'De Magnete' in which he showed that earth itself was a great magnet; a fact of great importance to all seafaring men and, as we shall see later, of central significance in I.G.Y. Later, in 1697-1700, Edmond Halley, a former Secretary and Assistant Secretary of Royal Society, made magnetic observations from ship named Paramour, and on basis of his measurements made a map of mag? netic declination over a portion of earth's surface. The earth's magnetic field is still studied very carefully and we know that position of magnetic poles changes slowly. Magnetic instruments have also told us of sudden increases in magnetic values, due to forces outside earth itself, and these are known as magnetic storms. Halley, who is perhaps best remembered for famous comet which bears his name, was a pioneer in examining other phenomena connected with planet Earth. In Philosophical Transactions of Royal Society in 1716 he offered one