It gave mean solar time, mean sidereal time, equation of time, and could chart the phases of the moon.

表盘上不仅能显示平太阳时，还能显示平恒星时、时差，记录月相。

This is called a Sidereal year, Sidereal meaning with respect to the stars where an external observer would be.

这被称为恒星年，恒星的意思是外部观察者所在的恒星。

If we measure the amount of time between two equinoxes, it ends up being 21 minutes shorter than a sidereal year.

如果我们测量两个春分点之间的时间量，最终会比恒星年短 21 分钟。

So instead, astronomers use Sidereal time for their telescopes to ensure that they're looking at the same region of space each night.

因此，天文学家使用望远镜的恒星时间来确保他们每晚都观察到同一空间区域。

So it makes no sense to use Sidereal time on earth, because six months down the line, day and night would be completely swapped.

因此， 在地球上使用恒星时间是没有意义的，因为六个月后， 白天和黑夜将完全互换。

And all geostationary satellites, like those used for communication or navigation, they use Sidereal time to keep their orbits locked with the Earth's rotation.

所有对地静止卫星， 例如用于通信或导航的卫星，都使用恒星时来保持其轨道与地球自转锁定。

Kepler's third law states that the squares of the sidereal periods of revolution of the planets are directly proportional to the cubes of their mean distances from the Sun.

开普勒第三定律指出，行星公转周期的平方与它们到太阳的平均距离的立方成正比。

That means if we based our calendar on sidereal years, the seasons would quickly get out of sync, Christmas would end up in July, dogs and cats, living together, mass hysteria!

这意味着如果我们的日历基于恒星年，季节很快就会不同步，圣诞节将在七月结束， 狗和猫一起生活，集体歇斯底里！

The amount of time it takes a star or constellation to reach the same point in the sky at the same time of day is 365 days 6 hours 9 minutes 9.76 seconds, or a sidereal year.

一颗恒星或星座在一天的同一时间到达天空中的同一点所需的时间是 365 天 6 小时 9 分 9.76 秒，或恒星年。