The active processes on the Sun derive from highly powerful pulse sources of electromagnetic or corpuscular radiation generated by the thermonuclear processes within the Sun. Electromagnetic radiations of the disturbed sites on the Sun are characterized by a wide band. In years of maximum solar disturbance there is a marked increase in the emission of X-ray as well as ultraviolet and infrared radiation. The intensity of ultraviolet radiation from the chromosphere of giant flares is hundreds of thousands and even millions of times greater than the intensity of ultra violet radiation from the solar surface. Solar radiation in the infrared spectral region was discovered fairly recently. This discovery gave rise to the new science of radioastronomy. Solar radioastronomy comprises the study of radio waves emitted by the active areas of the Sun. These studies are performed with the aid of radiotelescopes, i, e., huge antennas of different shapes which detect solar radio waves of wavelengths ranging from 20m to a few millimeters. It is now firmly established that the intensity of solar radio emission varies in direct proportion to the size of the sunspots, and to the power and intensity of the sudden flares, bursts, and explosions on the Sun's surface. At the stage of maximum solar activity the intensity of radio radiation from large spots is occasionally millions of times greater than the radiation level recorded during "quiet" periods. In addition to a "Sun bureau" many countries have also organized a "solar-radio bureau" which forecasts certain terrestrial phenomena from the solar radiowaves.
In addition to light, roentgen, ultraviolet, and radio radiations, the Sun also emits into interplanetary space, from its disturbed areas, streams of electrically charged particles of positive or negative polarity with ultrahigh energies. A solar corpuscular stream extending over an area with a cross section of hundreds of thousands of square kilometers travels the distance between the Sun and the Earth in about a day, and bombards the upper layers of our atmosphere. During maximum solar activity these streams suddenly gain an extremely high momentum.
As an example, on 29 March 1960, at 0940 hr Moscow time , a strong chromospheric flare was observed in the region of a group of sunspots.
At 1200 hr on 31 March a strong geomagnetic and ionospheric storm set in, accompanied with intense auroras in the middle latitudes. On 1 April shortwave radio communications were disrupted for several hours in the northern, middle, and southern latitudes. Communication between Europe and America, as well as between several European cities, was cut off.
The lower boundaries of the biosphere are not reached by the entire spectrum of solar radiation. The upper ionized layers of the terrestrial atmosphere intercept part of the electromagnetic band of solar radiation.
Waves of up to 20m partially penetrate these layers and reach the Earth's surface in an attenuated state. The depth of penetration of the solar corpuscular radiation into the terrestrial atmosphere is not yet definitely known. On the basis of numerous theoretical and experimental studies it may be assumed that solar corpuscular streams, while ionizing the upper layers of the terrestrial atmosphere, lose their speed and are deflected by the terrestrial magnetic field and thus, the corpuscular solar radia tion does not reach the biosphere. Nevertheless, it is assumed that
certain solar corpuscles having the high energy of cosmic rays may reach the Earth's surface. However, it cannot be assumed that all electro magnetic and corpuscular radiations of the Sun are known to modern science.
On the basis of their observations, several prominent scientists of the nineteenth and early twentieth centuries, including Svante Arrhenius, Fridtjof Nansen, and others, not only assumed the possibility of a direct effect of solar storms on certain phenomena in the troposphere, and parti cularly in the organic world, but actually established a series of correla tions. The relationship between the solar activity cycle and phenomena of the organic world was successfully studied in Russia before the revolution, and is now being investigated in the Soviet Union by numerous scientists, including F. M. Shvedov, N. A. Skalovskii, N. M. Kulagin, D. O. Svyatskii, P. Yu. Shmidt, A. P. Moiseev, G. A. Ivashentsov, V. B. Shostakovich, S. T. Vel'khover, A. A. Sadov, G. I. Pokrovskii, E. A. Slutskii, N. S. Shcher binovskii, N. A. Shul'ts, N. V. Romenskii, and others. The scientific value of such investigations was described by Prof. M. S. Eigenson in his article "Recent Trend in Space Biology,"* and in his "Essays on the Physicogeo graphical Manifestations of Solar Activities."** This field of science is gradually achieving its legitimate place among the natural sciences. In countries outside the USSR this science has been enriched by numerous investigations in "heliobiology" (Oenstrom, Hallend-Hansen, Lemstrom, Hahn, Fritz, Shaw, Faure, Hiitington, Douglass, Morill, Memory, Ballou, win, Amman, Smitt, Kritzinger, Morrill, Dull, Takata, Murazugi, Budai, Denier, L. Schluck, Reinhold, Edward Dewey, Helmut Berg, and others).
In 1915 the author of this article / 1 / energetically undertook, for the first time in the history of science, to make a break-through in this field, selecting the following two research trends which seemed to be the most promising: studies of changes in the functional state of the human nervous system under the effect of solar factors /1, 4, 6, 14, 15, 23, 25-28, 30, 31, 40, etc.!, and studies of the world statistics of epidemic diseases, where the large numbers could facilitate detection of the reflected effect of solar disturbances. Indeed, a certain parallelism was soon established between the incidence of most pandemics and epidemics in the course of the 16th to 19th centuries (cholera, grippe, plague, diphtheria, relapsing fever, and cerebrospinal meningitis) and the solar activity cycle /5, 6, 10, 13, 16, 19, 41, 51, 57, 59, 60-64, 70, 72-78, 80/. The correlation coefficient between the solar and the epidemiological curves often reaches values of 0.8-0.9 (Figures 2-7). Although incidence of epidemic diseases is closely linked with socioeconomic conditions and numerous other factors, such as sanitation facilities, housing, nutrition, war, famine, unemploy ment, etc., these conclusions have been confirmed by thousands of studies and are unquestionably accurate.