Aphelion

Aphelion, the point in the orbit of an object in the solar system that is farthest away from the sun.

The earth’s aphelion is about 153 million km (about 95.1 million mi) away from the sun. Because the earth has an almost circular orbit, this distance is only about 3 million km (about 1.9 million mi) farther away from the sun than the earth’s average distance from the sun. The earth’s aphelion is only about 5.9 million km (about 3.8 million mi) farther away from the sun than its perihelion, or the orbit’s closest point to the sun. Pluto has the most dramatic difference between its aphelion and its perihelion of any planet in the solar system at 2.96 billion km (1.84 billion mi).

The earth’s aphelion occurs in the month of July, while its perihelion occurs in January, although the earth’s distance from the sun has little to do with seasons. Instead, the tilt of the earth on its axis causes seasonal climate changes. The speed at which the earth moves around the sun varies slightly depending on the position of the earth in its orbit—it moves faster at perihelion than at aphelion.

Aphelion only refers to objects orbiting the sun. The point in the orbit of a body circling the earth in which the body is farthest from the earth is called the apogee.