What are the subtle, long-term deviations in a planet's path from a perfect Keplerian ellipse called?

Answer

Perturbations

Perturbations are the minor, continuous nudges caused by the gravitational influence of other large bodies in the Solar System, causing the actual path to slightly deviate from the ideal, mathematically stable ellipse.

What are the subtle, long-term deviations in a planet's path from a perfect Keplerian ellipse called?

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Orbit of the Planets in the Solar System - YouTube

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