IV. Our place in the universe

1. We know that the earth is one of nine major satellites of the sun, and that the sun is only one of countless stars in the Milky Way Galaxy. In turn, there are unnumbered galaxies in the universe. When we consider that the earth at its nearest point is some 91,350,000 miles from the sun, and the distances of other stars are so great that they must be measured in light years, we can appreciate the comparative smallness of our earth.

2. For many centuries men held the belief that the earth was the centre of the universe. The interesting fact is that as early as 270 B.C. a Greek astronomer, Aristarchus of Samos had the idea that the earth turned once a day on its axis and also moved around the sun. This idea of Aristarchus' did not gain wide acceptance in his time. People preferred to believe, as the great teacher Aristotle did, that the world was the centre of the universe.

3. Now we know that not only does the earth revolve around the sun, but the sun also is in motion. Like the earth, the sun both rotates and revolves. Once every 27 days it rotates on its axis and, with other stars, it travels in a great spiral in the Milky Way Galaxy. The movements of the earth, moon, sun, and stars take place with precise regularity. Thus we keep time by them.

4. We receive light and warmth from the sun. The position of the sun in the sky determines the angle at which its rays strike the earth. The angle at which the sun's rays strike the surface is important because the higher the angle, the more heat there is concentrated in an area. Within the tropics, for example, the sun is always high in the sky at noontime. In the high latitudes, the sun is lower in the sky. Therefore we can expect that the tropics receive more intense heat from the sun than the high latitudes. Because the earth is inclined on its axis as it goes about the sun, all places on earth do not receive the same amount of heat and light. Near the equator, where the sun is in the sky for about twelve hours, the number of hours of daylight are about equal throughout the year.

5. Variations in the amount of solar energy received by different parts of the earth have many results. The uneven heating of the atmosphere helps to produce winds and rain, and the waters of the great oceans are caused to circulate in certain patterns. A chain of reactions is set up which leads to the establishment of various types of climate and vegetation conditions around the world. These, in turn, affect man's life on earth in many ways. We are affected by the sun in more ways than are ordinarily recognized.

V. Soviet scientists study earth's weather and the sun

The evidence for effects of solar activity on the climate and weather of the earth is becoming stronger, although the mechanisms for these effects are not fully explained. At long last Anatoly V. Dyakov has won official recognition in the Soviet Union for his theories of long-range weather forecasting - that solar activity influences weather not only through variations in heat flux, but also through other forms of radiation. Dyakov asserts that the sunspot activity and variations in the solar wind should also be taken into account in long-range forecasting.

Earlier evidence of solar influence was from systematic variations in the widths of growth rings in trees with the solar cycle. Later, the Soviet scientists found similar evidence in variable silt deposit layers in the Aral Sea and Lake Victoria, which they claim can be used to trace the solar cycle back for millions of years. The Soviet scientists also claim that large cyclones and anti-cyclones tend to form in a band around the magnetic north pole. American scientists have evidence for the regular formation of a large low pressure trough in the North Pacific after unusual particle influx from the sun. This subsequently leads to extended storm systems across the United States and Canada.

To be read after Sections 6 — 7