This is another pick from the wide spectrum of George Bayer's work and interests, written years before the ascend of modern space technology and space physics. It was not until the 19th century, some 200 years after Galileo's invention of the telescope and discovery of sunspots, that the systematic scientific study of the Sun began. During the second half of the 20th century, correlations reported between solar activity (as manifested in the changing sunspot number and in flares), disturbances in the Earth’s magnetic field, and auroral activity clearly suggested the existence of a physical connection between the Sun’s activity and terrestrial magnetic and upper atmospheric phenomena.
The nature of this connection — one of the central themes of space physics — became the subject of intense study and controversy during the first half of the 20th century. By mid-century, the prevailing theory involved ionized “corpuscular streams” from the Sun that traveled at speeds of 1,000 to 1,600 kilometers per second and within which the geomagnetic field formed a cavity. This picture was changed dramatically in the late 1950s when it was shown theoretically that the outer solar corona could not be static but must be continually expanding outward. The model of individual corpuscular streams was replaced by the modern concept of a continuous solar wind. Of fundamental importance for the field of solar-terrestrial research were the prediction and discovery during the first decade of the space age of a link between geomagnetic activity and the orientation of the magnetic field embedded in the solar wind (the IMF). During the ensuing decades, space physicists made significant progress in understanding this link, which involves the merging of the interplanetary and terrestrial magnetic fields and the consequent transfer of energy, mass, and momentum from the solar wind into the magnetosphere, often resulting in major disturbances of Earth’s space environment. See also HERE
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| Source: George Bayer (1939): Preview of Markets for January 1940 (Vol. 1, No. 8); Carmel, California. |