aphelions

Aphelion refers to the point in the orbit of a celestial body, most commonly a planet, at which it is farthest from the Sun. This term is derived from the Greek words "apo" meaning "away" and "helios" meaning "sun". The opposite point in an orbit, where the celestial body is closest to the Sun, is called perihelion.

The Earth's aphelion occurs around July 4th each year. While aphelion is the point of greatest distance from the Sun, it does not necessarily correspond to the coldest time of the year for a hemisphere. Earth's seasons are primarily caused by the tilt of its rotational axis, which is approximately 23.5 degrees relative to its orbital plane. During aphelion, the Northern Hemisphere is tilted towards the Sun, experiencing summer, while the Southern Hemisphere is tilted away, experiencing winter.

The distance of celestial bodies from the Sun varies due to their elliptical orbits. The degree of this variation is determined by the eccentricity of the orbit. An orbit with higher eccentricity will have a more significant difference between aphelion and perihelion distances. The aphelion and perihelion distances are important parameters in calculating the orbital elements of planets, comets, and other objects within a solar system.