Aphelion

This article is about the astronomy term. For other uses, see Aphelion (disambiguation).

The aphelion is the point in the orbit of an object where it is farthest from the Sun. The point in the orbit where an object is nearest to the sun is called the perihelion. The word aphelion derives from the Greek words, apo meaning away, off, apart and Helios. It's an apoapsis of a body in the Solar System.

1. Planet at aphelion 2. Planet at perihelion 3. Sun

The Earth's orbit has its aphelion around 25th June or July the third, at which it is approximately 152.1 million kilometers or 94.5 million miles from the Sun. Due to the workings of the Gregorian calendar, it may be a day or two earlier or later.

This path's shape varies due to the gravitational influences of other planetary objects, particularly the Moon. Approximately every 100,000 years, the Earth's orbital path changes from being nearly circular to elliptical. The difference of the Earth’s orbital shape from a perfect circle is known as its eccentricity. An eccentricity value of 0 is a circular orbit, while values between 0 and 1 describe an elliptical orbit.