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

THE ARCTIC REGIONS. 51 practically a home in the regions round about the North Pole, and not merely the Polar point, we must now see what modi- fications are necessary to be made in the above characteristics owing to the observer being stationed a little to the south of the North Pole. We have seen that at the Pole the northern hemisphere is seen spinning round the observer, and all the stars move with it in horizontal planes without rising or setting; while the other celestial hemisphere is always invisible. But when the observer is shifted downwards, his zenith will no longer corres- pond with the Pole Star, nor his horizon with the celestial equator. For instance let Z, in the annexed figure, be the zenith of the observer, and P the celestial North Pole. When the ob- server was stationed at the terrestrial North Pole, his zenith coincided with P, and his horizon with the celestial equator, with the result that all the stars in the dome Q'PQ revolved round him in horizontal planes. But when the zenith is shifted to Z, this state of things is at once altered, as the heavens will revolve, as be- fore, round the line POP', and not round the zenith- line ZOZ'. When the ob- server was stationed at the North Pole these two lines coincided, and hence the circles of revolution des- cribed by the stars round the celestial Pole were also described round the zenith-line. But when the zenith Z is different from P, as in the figure, the celestial horizon of the observer will be H'H,