The Arctic Home in the Vedas c5.13

c5.13

But this axis describes a small circle round the pole of the ecliptic in a cycle of 25,868 years, giving rise to what is called the precession of the equinoxes, and consequently the inclination of the earth's axis to the plane of its orbit is not always the same at any given point in its orbit during this period. This causes the seasons to occur at different points in the earth's orbit during this great cycle. Thus if the winter in the northern hemisphere occurred when the earth was at *P* at one time, some time after it will occur at *p* and the succeeding points in the orbit until the end of the cycle, when it will again occur at *P*. The same will be the case in regard to summer at the point *A* and equinoxes at *Q* and *Q'*. In the diagram the dotted lines *q q'* and *p a* represent the new positions which the line *Q Q'* and *P A* will assume if they revolve in the way stated above. It must also be noted that though the winter in the northern hemisphere may occur when the earth is at *p* instead of at *P*, owing to the aforesaid motion of its axis, yet the orbit of the earth and the points of perihelion and aphelion are relatively fixed and unchangeable. Therefore, if the winter in the northern hemisphere occurs at *p*, the earth's distance from the sun at the point will be greater than when the earth was at *P*. Similarly, in the course of the cycle above mentioned, the winter in the northern hemisphere will once occur at *A*, and the distance of the earth from the sun will then be the longest. Now there is a vast difference between a winter occurring when the earth is at *P* and a winter occurring when it is at *A*. In the first case, the point *P* being nearest to the sun, the severity of the winter will be greatly modified by the nearness of the sun. But at *A* the sun is farthest removed from the earth, and the winter, when the earth is at *A*, will be naturally very severe; and during the cycle the winter must once occur at *A*. The length of the cycle is 25,868 years, and ordinarily speaking half of this period must elapse before the occurrence of winter is transferred from the earth's position at *P* to its position at *A*. But it is found that the points *P* and *A* have a small motion of their own in the direction opposite to that in which the line of equinoxes *QQ'* or the winter point *p* moves along the orbit. The above cycle of 25,868 years is, therefore, reduced to 20,984, or, in round number, 21,000 years. Thus if the winter in one hemisphere occurs when the earth is at *P*, the point nearest to the sun in the orbit, it will occur in the same hemisphere at *A* after a lapse of 10,500 years. It may be here mentioned that in about 1,250 A. D., the winter in the northern hemisphere occurred when the earth in its orbit was at *P*, and that in about 11,750 A. D. the earth will be again at *A*, that is, at its longest distance from the sun at the winter time, giving rise to a severe winter. Calculating backwards it may be seen that the last severe winter at *A* must have occurred in the year 9,250 B. C.¹ It need not be mentioned that the winter in one hemisphere corresponds with the summer in the other, and that what is said about winter in the northern hemisphere applies *mutatis mutandis* to seasonal changes in the southern hemisphere.