Hi everyone,

when you compute earth's mean anomaly from mathematica's astronomical data over a period of time it appears to move to fast:

FromDMS /@ 
 PlanetData["Earth", 
  EntityProperty["Planet", 
     "MeanAnomaly", {"Date" -> #}] & /@ {DateObject[{2023, 1, 1, 0, 0,
       0}, TimeZone -> "Europe/London"], 
    DateObject[{2024, 1, 1, 0, 0, 0}, TimeZone -> "Europe/London"]}]

The result given is {356.374, 358.018} (angles modulo 360), and this amounts to an elliptic precession of 1.64396 degree per year. Earth should have that much in about a century. (There is nothing special about the dates chosen, the mean anomaly increases linearly as expected, but the slope is slightly too high.)

Do I have some sort of misconception, or is there some trouble with the data?

Yours,

Bernd.