Source: Vitalik1986 (2011, March 26). Perihelios-aphelion. wikimedia commons. https://commons.wikimedia.org/w/index.php?curid=14702160
Short definition:
The point in the orbit of a planet or other celestial body that is farthest from the sun.
Detailed Definition:
Aphelion is the point in the orbit of a celestial body where it is farthest from the sun. It is the opposite of perihelion, which is the point in the orbit where the celestial body is closest to the sun. The distance between a celestial body and the sun varies during its orbit due to the elliptical shape of the orbit. The aphelion is the point where the distance is at a maximum.
Etymology:
aphelios - far from the sun
aph - from and helion - the sun
Sample Sentence(s):
"Mars reaches its aphelion in July, when it is about 250 million miles from the sun."
"The aphelion of Earth's orbit occurs in July, when it is about 3.1 million miles farther from the sun than at perihelion in January."
"The aphelion of Pluto's orbit is about 49.3 billion kilometres, while its perihelion is about 29.7 billion kilometres."
