Aphelion
Aphelion is the point in the orbit of an astronomical object around the Sun at which the object is farthest from the Sun. For bodies in bounded orbits, such as planets, asteroids, and comets, the orbit is approximately an ellipse with the Sun at one focus; the farthest point along the orbit is called aphelion, the opposite point being perihelion.
In an elliptical orbit, with semi-major axis a and eccentricity e, the distance at aphelion is a(1+e)
Earth provides a notable example. Its orbital semi-major axis is about 1 astronomical unit (AU), and its
The term aphelion is used for orbits around the Sun; there is no finite aphelion distance for