# 地球自转

## 地球自转的规律性

### 规律性

• 圆锥轴线垂直地球公转轨道平面，指向黄道两极。
• 圆锥的半径黄赤交角
• 运动的方向是自东向西，即同地球自转的方向相反。
• 运动的速度是每年50.29角秒，周期約25800年。

## 註解

1. ^ When Earth's eccentricity exceeds 0.047 and perihelion is at an appropriate equinox or solstice, only one period with one peak balances another period that has two peaks.[2]
2. ^ Aoki, the ultimate source of these figures, uses the term "seconds of UT1" instead of "seconds of mean solar time".[17]
3. ^ Sidereal day is arguably a misnomer because the dictionary definition of sidereal is "relating to the stars", thus fostering confusion with the stellar day.
4. ^ In astronomy, unlike geometry, 360° means returning to the same point in some cyclical time scale, either one mean solar day or one sidereal day for rotation on Earth's axis, or one sidereal year or one mean tropical year or even one mean Julian year containing exactly 365.25 days for revolution around the Sun.
5. ^ See Fallexperimente zum Nachweis der Erdrotation（German Wikipedia article）.

## 參考資料

1. ^ Derivation of the equation of time
2. ^ 2.0 2.1 Jean Meeus, Mathematical astronomy morsels (Richmond, Virginia: Willmann-Bell, 1997) 345–6.
3. ^ Equation of time in red and true solar day in blue
4. ^ The duration of the true solar day
5. ^ Leap seconds by USNO
6. ^ 6.0 6.1 6.2 6.3 IERS EOP Useful constants
7. ^ Explanatory Supplement to the Astronomical Almanac, ed. P. Kenneth Seidelmann, Mill Valley, Cal., University Science Books, 1992, p.48, ISBN 0-935702-68-7.
8. ^
9. ^ IERS Variations in the duration of the day 1962–2005
10. ^ Arthur N. Cox, ed., Allen's Astrophysical Quantities p.244.
11. ^ Michael E. Bakich, The Cambridge planetary handbook, p.50.
12. ^ Permanent monitoring
13. ^ Sumatran earthquake sped up Earth's rotation, Nature, December 30, 2004.
14. ^ Wu, P.; W.R.Peltier. Pleistocene deglaciation and the earth's rotation: a new analysis. Geophysical Journal of the Royal Astronomical Society. 1984, 76: 753–792.
15. ^ Physical effects
16. ^ Why do planets rotate?. Ask an Astronomer.
17. ^ Aoki, et al., "The new definition of Universal Time", Astronomy and Astrophysics 105 (1982) 359–361.