In astrology, a diurnal arc is the time, as expressed in right ascension, it takes a planet, point, or degree to move from its rising point to its setting point. This takes place in many celestial bodies such as the sun and moon.
网络释义
1、[天]周日弧
... 周日加速度：diurnal acceleration 周日弧：diurnal arc 周日航行定位工作：day's work ...