December 31, 1965, brought to a close the International years of the Quiet Sun (IQSY 1964-1965). The rich harvest of scientific results produced by this intensive study of the vast region between the sun and the earth will be published in a series of about 7 volumes, of which this is the fifth, under the general title of Annals of the IQSY. The series should be completed by 1969. The General Editorial Board for this project consist of 19 distinguished scientists gathered from 10 countries, with Professor W. J. G. Beynon as Chairman and Dr. A. C. Stickland as General Editor.
The IQSY was sponsored by the International Council of Scientific Unions. Its geophysical and solar observations were carried out by scientists in more than 70 countries. Since the dates of the IQSY were chosen to coincide with the period of minimum activity in the 11-year solar cycle, the results obtained from a complement and counterpart to those obtained in the International Geophysical Year (IGY 1957-1958), when the sun was in the most agitated state ever observed.
The proved success of efforts toward better international cooperation, at least in the sciences, was not the least of the triumphs of the IQSY. Indeed, without this cooperation, such a program would not have been physically feasible, since it demanded round-the-world, round-the-clock observations at widely scattered tracking stations, space radar and radio receivers, and observatories. The “patrols” undertook a constant optical and instrumental watch on the sun; they photographed its spots, coronal fluctuations, plagues, and prominences; and they measured the entire spectrum of solar of solar radiation: gamma and X-rays, visible and radio emissions. The effects of solar radiation and charged particles on the earth and its environment were an important aspect of these studies, especially since, in quiet years, solar outbursts are fewer in number, and hence the secondary effects do not seriously overlap and conflict with each other.
Some of the more dramatic experiments:
-Satellites (including orbiting solar observatories) and space probes designed to measure the “solar wind” (streams of high-speed electrons and protons emitted by the sun), and the gamma rays and X-rays that cannot penetrate our atmosphere without undergoing changes.
-High-powered radar contact with the sun and its corona.
-A balloon-carried coronagraph (a telescope designed to block out the direct image of the sun) to photograph the corona from a point above most of the earth's distorting atmosphere.
-A mapping of the contours of the sun's radio image
-A series of heliograms to map out the distribution of separate elements in the sun's atmosphere.
-Measurements of the effects of solar fluctuations on the earth's magnetic field and atmosphere; for example, the action of solar X-rays in reducing the ionosphere's ability to reflect short radio waves (a study of considerable practical interest, since the normal reflectivity of the ionosphere causes radio signals to be bounced around the world, and this work could lead to more reliable predictions of the blackout of radio communications).
-Studies of geomagnetically trapped radiation, and the study of galactic cosmic rays in relatively pure form, the sun's contribution to changes in the characteristics of these rays being at a minimum in quiet periods.
Other studies center on airglow, the aurora, the earth's heat budget, and high-altitude circulation in the atmosphere.
