How does perihelion occur?

A planet's orbit around its sun is roughly shaped like an ellipse, with the sun at one of the foci. Every orbit, the planet is at its closest point to the sun, a phenomenon known as perihelion.

Precession is another phenomenon that occurs in planetary orbits, meaning that the interval between succeeding perihelia lengthens with each orbit.

Because of the other planets' gravitational pull, planetary orbits are not true ellipses.

Earth's perihelion occurs approximately on January 3rd, though due to other planets' gravitational pull, it can actually happen between January 2nd and January 4th.

A celestial body, like a planet, reaches perihelion when it is at its closest point to the Sun in its orbit. The planet moves more quickly toward the Sun and more slowly away from it because of the gravitational attraction between the two.