Analysis of Common Phenomena and Reasons for Changes in the Earth’s Rotation Speed

In recent years, long-term observations and studies by researchers have shown that: (1) the Earth's rotation has seasonal variations and periodic changes with cycles of half a year and a year; (2) the Earth's rotation speed is gradually slowing down; (3) there is a strong correlation between the solar orbital motion and changes in the Earth's rotation rate; (4) the Earth's core is rapidly rotating in the opposite direction. What are the reasons for these phenomena? This paper analyzes the gravitational interactions between celestial bodies, proposes the concept of an equivalent spherical surface for the emission of gravitational particles from celestial bodies, and discusses the separation phenomenon between the gravitational focus and the centre of mass. Taking the Sun-Earth system as an example, the point of gravitational influence of the Earth by the Sun is at 0.5 radii on the side of the Earth closest to the Sun. Due to the separation between the Sun-Earth gravitational influence point and the Earth's centre of mass, the gravitational influence of the Sun on this point causes the Earth to experience a centripetal force that orbits the Sun, while simultaneously generating a force that causes the Earth to rotate in the opposite direction around the gravitational influence point. Under the combined effect of the Earth's inertial force while orbiting, the centripetal force towards the Sun, and the force of the Earth's reverse rotation around the gravitational influence point, the Earth's revolution leads to an elliptical orbit. This paper simulates the elliptical orbit of the Earth around the Sun. Through calculations and simulations, it is found that 99.99% of the Earth's gravitational influence from the Sun is used for the Earth's rotation. This essentially identifies the intrinsic reasons for variations in the Earth's rotation. This paper argues that the seasonal periodic variations in the Earth's rotation, the long-term slowdown, and the rapid reverse rotation of the Earth's core are all closely related to the changes in the Sun's orbit and the separation phenomenon between the Sun's gravitational influence point and the Earth's centre, being inevitable results of the Sun's gravity being almost entirely applied to the Earth's rotation. Keywords: seasonal periodic variations in the Earth's rotation; long-term slowdown of the Earth's rotation; changes in the Earth's rotation strongly related to solar orbital motion; rapid reverse rotation of the Earth's core; separation phenomenon between celestial gravitational focus and centre of mass.