安清翘关于岁差的认识

岁差是中西天文学史上极其重要的概念。19世纪初的中国学者安清翘对流行于我国明清直到鸦片战争之后的托勒密的岁差理论予以了反驳,并由此独立于近代西方建立起地心体系下关于岁差原因的解释,即黄道轴周日沿自东而西即逆时针的左旋方向自转(本体正转)一周的同时也绕北极自东而西圆锥形地公转(斜转)一周,由于这种自转稍迟于其公转,作为相对运动的结果,反而是黄极环绕北极(赤极)的缓慢东移,这就是岁差产生的原因。就视运动而论,安清翘关于岁差的解释与现代的岁差理论其实是一种相对运动的关系,即北极绕黄极转和黄极绕北极转在效果上是等价的。

An Qingqiao's Explanation of Precession

As an important concept in astronomy, precession attracted much attention in history in both China and the West. The ancient Greek astronomer Ptolemy attributed precession to the slow movement of all fixed stars from west to east around the earth. Since the introduction of precession in China via Western missionaries in late Ming Dynasty, Ptolemy's explanation of it was very prevalent during the Ming and Qing Dynasties until after the Opium Wars. However, in the early 1800s, an interval of intercommunion between China and the West from 1723 to 1840, the Chinese scholar An Qingqiao refuted Ptolemy's viewpoint. In his work named Tui Bu Wei Shi written in 1811, which means that the study of astronomy must be based on the observation of celestial phenomena, a new theory was developed to further elucidate precession in geocentric system, quite independent of modern West, especially Newton's explanation of gravitation. That is, at the same time of self-rotating from east to west, the axis of ecliptic pole also completes a circle around the north pole of heaven at an appreciably faster speed in the same direction, and thus as a result of relative motion it slowly moves eastward around the north pole instead to cause precession phenomenon. Related to the visual motion of procession, An Qingqiao's viewpoint is linked to the current conclusion by a relationship of relative movement,since the results are the same between the revolutions of north pole around ecliptic pole and ecliptic pole around the north pole. Via the ideas and achievement of An Qingqiao, at least two facts further prove to some extent that Chinese scholars are of the same creativity as the ones in the West, and that a correct conclusion may be also drawn even in a theory which is now proven to be wrong. In the case of An Qingqiao, the wrong theory or precondition is the geocentric system related to the universe.