Perihelion of the Earth

[ricci]

The motion of the Earth around the Sun, and that of the others planets, isn't constant, but varies between 362d19h18m and 368g4h9m. Indeed if you see the table below, the perihelion's day is not the same. What is the reason for this difference? ...

www.pierpaoloricci.it/dati/perielioterra_eng.htm

[Archy]

The position of the other planets

[wasyoungonce]

Probably many things, mainly gravitation & possibly precession as the earth is a very large gyroscope.