日食发生条件的计算

从天文学角度对日食形成原理及其形成条件进行了研究计算，认为日食形成的两个条件——月球黄纬条件与日食限角条件分别从不同角度反映了日食时月球距黄道的角距离或太阳距黄白交点的角距离，直接或间接地体现了它们与黄白交角、日月视半径及其地平视差的关系．而日月视半径及其地平视差又随日地距离与月地距离的变动而变化，黄白交角也是变动的．因此，从根本上讲，日食时月球黄纬与日食限角的大小均取决于黄白交角的大小及日地距离与月地距离的远近，两者本质上一致的．

The calculation for conditions of forming solar eclipse

The principle and the conditions of forming solar eclipse are calculated from the point of view of astronomy.It is considered that the two conditions coused solar eclipse-the moon ecliptic latitude and the solar eclipse limit,show the angle pitch from the moon to the ecliptic or the angle pitch from the sun to the node of the ecliptic and the moon's path from different anyles.They also show the relations between the node of the ecliptic and the moon's path,the apparent r adius of the sun and the moon,and it's horizontal parallax directly or indirectly.The apparent radius and it's horizontal parallax changes with the distance to the earth from the moon or from the sun.The angle of skew of the ecliptic and the moon's path are changeable, too.The angle of the moon ecliptic latiude and the solar eclipse limit depend on the angle of skew of the ecliptic and the moon's path and the distance to the earth from the moon or from the sun.The two aspects are basically consistent.