# 地球自转

（重定向自地軸

## 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".[7]
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 （German Wikipedia article）.

## 參考資料

1. ^ Derivation of the equation of time. [2010-10-08]. （原始内容存档于2010-09-24）.
2. Jean Meeus, Mathematical astronomy morsels (Richmond, Virginia: Willmann-Bell, 1997) 345–6.
3. ^ Equation of time in red and true solar day in blue. [2010-10-08]. （原始内容存档于2010-10-09）.
4. ^ The duration of the true solar day. [2010-10-08]. （原始内容存档于2009-08-26）.
5. ^ Leap seconds by USNO. [2010-10-09]. （原始内容存档于2012-05-27）.
6. IERS EOP Useful constants. [2010-10-09]. （原始内容存档于2012-11-03）.
7. ^ Aoki, et al., "The new definition of Universal Time页面存档备份，存于互联网档案馆）", Astronomy and Astrophysics 105 (1982) 359–361.
8. ^ Explanatory Supplement to the Astronomical Almanac, ed. P. Kenneth Seidelmann, Mill Valley, Cal., University Science Books, 1992, p.48, ISBN 0-935702-68-7.
9. ^ IERS Excess of the duration of the day to 86,400s…since 1623页面存档备份，存于互联网档案馆） Graph at end.
10. ^ IERS Variations in the duration of the day 1962–2005. [2007-08-13]. （原始内容存档于2007-08-13）.
11. ^ Arthur N. Cox, ed., Allen's Astrophysical Quantities页面存档备份，存于互联网档案馆 p.244.
12. ^ Michael E. Bakich, The Cambridge planetary handbook页面存档备份，存于互联网档案馆, p.50.
13. ^ Permanent monitoring. [2010-10-11]. （原始内容存档于2010-11-15）.
14. ^ Sumatran earthquake sped up Earth's rotation页面存档备份，存于互联网档案馆）, Nature, December 30, 2004.
15. ^ 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.
16. ^ Why do planets rotate?. Ask an Astronomer. [2010-10-08]. （原始内容存档于2007-06-09）.