Nutational motion refers to the slight, periodic oscillation of the Earth's axis as it rotates. This motion occurs due to the gravitational forces exerted by the Moon and the Sun on the Earth's equatorial bulge. As a result, the axis of the Earth wobbles in a circular pattern, completing a full cycle approximately every 18.6 years. This phenomenon is part of a broader category of movements known as precession, which also includes the gradual shift of the Earth's rotational axis over long periods. Nutation affects various aspects of Earth science, including astronomy and geodesy, as it influences the precise positioning of celestial objects and the measurement of the Earth's shape.