Year. The Solar or Tropical Year is the period of time in which the earth performs a revolution in its orbit about the Sun, or passes from any point of the ecliptic to the same point again. It consists of 365.2422 days, or 365d 5h 48M 46s. (The Sun's motion in longitude in a Julian year of 365.25 days is 360° 27'7.)

The Sidereal Year is a period of 365d.256 or 365d 6h 9m 9s.5, during which time the Sun's center, departing eastward from the ecliptic meridian of a given star, returns to the same; an astral year. It is about 20 minutes longer than the tropical year. The sidereal month is of a duration of 27d.322. The Anomalistic Year, that between two successive perihelion passages of the Earth, is 365d.26, or 4m 43s.5 longer than the sidereal year, although it is increasing in length even faster than the sidereal year. v. Day.