格林尼治太阳（恒星）时

Sidereal time is the measure of the earth's rotation with respect to distant celestial objects. Compare this to UT1, which is the rotation of the earth with respect to the mean position of the sun. One sidereal second is approximately 365.25/366.25 of a UT1 second. In other words, there is one more day in a sidereal year than in a solar year.

恒星时是指相对于恒星的地球自转角度的度量。UT（世界时）中恒星为太阳。

恒星时是春分点和当地子午线之间的小时角。

根据规则，格林尼治恒星时度量的参考点是格林尼治子午线和春分点（地球赤道和黄道的交点）。格林尼治恒星日从春分点和格林尼治子午线重合时开始。格林尼治平恒星时是春分点平均位置的小时角，忽略了春分点进动的短期波动。

 

 

计算格林尼治平恒星时的公式。其中JD为儒略日。

 

示例