1·Approximately, a year has 365 solar days but 366 sidereal days. Do you know why.
一年中大约有365个太阳日，但却有366个恒星日，你知道原因吗？
2·Sidereal age, the distance between they and earth, it is the conclusion that astronomy wants scrupulous to reach.
恒星的年龄，它们与地球之间的距离，都是天文学要一板一眼得出的结论。
3·A sidereal day is about 4 minutes shorter than a solar day.
一个恒星日比一个太阳日大约短4分钟。