The angular distance between two celestial bodies as seen from Earth. 距角从地球上看的两个天体之间的角距离
Angular distance is the distance between two objects measured as an angle from a given point. 角距离，是由一定点到两物体之间所量度的夹角。
The distance between the two rails of a railroad. 轨距铁路两根钢轨之间的距离
The distance between one peak or crest of a wave of light, heat, or other energy and the next corresponding peak or crest. 波长光、热或其它能量波的一个波峰或波谷与下一个对应的波峰或波谷之间的距离
