वेदों की प्राचीनता एवं काल-निर्णय / ओरायन (लोकमान्य बाल गंगाधर तिलक - खगोलीय वैदिक शोध)

52 • THE ARCTIC HOME IN THE VEDAS. and the stars will now appear to move in circles inclined to his horizon, as shown in the figure by the black lines AA', BH' and CC'. Some of the stars, viz., those that are situated in the part of the celestial dome represented by H'PB, will be visible throughout the night, as their circles of revolution will be above the horizon H'C'D'H. But all the stars, whose Polar distance is greater than PB or PH', will, in their daily revolution, be partly above and partly below the horizon. For instance, the stars at C and D will describe circles, some portions of which will be below the horizon H'H. In other words, the appearance of the visible celestial hemisphere to a person, whose zenith is at Z, will be different from the appearance presented by the heavens to an observer at the North Pole. The stars will not now revolve in horizontal planes, but obliquely. A great number of them would be circumpolar and visible during the whole night, but the remaining will rise and set as with us in the tropics, moving in oblique circles. When Z is very near P, only a few stars will rise and set in this way, and the difference will not be a marked one ; but as Z is removed further south, the change will become more and more apparent. Similar modifications will be introduced in the duration of day and night, when the observer's position is shifted to the south of the terrestrial North Pole. This will be clear by a reference to the figure on the next page. Let P be the celestial North Pole, and Q'Q the celestial equator. Then since the sun moves in the ecliptic E'E, which is inclined at an angle of about 23½° (23° 28' ) to the equator, the circles T'E and E'T will correspond with the terrestrial circles of latitude, called the Tropics, and the circle AC with the Arctic Circle on the terres- trial globe. Now as the sun moves in the ecliptic E'E, in his annual course he will always be twice over-head for an observer