An anomalistic year is the time in which Earth's anomaly increases by exactly 360 ° relative to the perihelium. Or simpler: it takes time for two consecutive perihelium passages of the Earth. The Kepler comparison makes a difference between the true, the eccentric and the middle anomaly, which makes no difference here.
Just as the direction of the spring point is not a fixed direction relative to the fixed stars (see: tropical year), the direction of Sun Perihelium is not a fixed direction. Over time, the ecliptic plane (or line of the apsides) rotates through the disturbances of other planets. The perihelium shifts (relative to the solid stars) in a direction opposite to the direction in which the spring tip shifts, thus in the same direction in which the Earth moves on the ecliptic. As a result, the Earth, leaving the perihelium, should rotate slightly more than 360 ° relative to the stars to get into the new perihelium (prolonged). The duration
The anomaly year takes 365,25964 days. We can deny it: Meeus published the equations to calculate the course elements of the main planets. The length of the perihelium, compared to the standard equinox of J2000.0, is one of these track elements. For the year 2000 this length is shown to increase by 0 °, 3225654 T + 0 °, 00014799 T per julian century or 11.6 arc seconds per year. T = 1 julian century of 36 525 days. Therefore, the Earth from perihelium to perihelium, relative to the solid stars, should describe an angle of 360 ° + 11 ", 6 or 1296011", 6.
The lateral year or describing an angle of 360 ° relative to the fixed stars takes 365,256 36 days. The anomaly year therefore takes 365,256 36 × 1 296 011,61 / 129 6000 or 365,259 64 days or 365d 6u 13m and 53s. This is 4m 43.4s longer than a lateral year and 25m 7.7s longer than a tropical year of the same time.
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