Noun
That point of a planet's or comet's orbit which is most distant from the sun, the opposite point being the perihelion.
Source: Webster's dictionaryBased on measurements of the aphelion and perihelion of the Earth and Mars, he created a formula in which a planet's rate of motion is inversely proportional to its distance from the Sun. Source: Internet
At the time of its discovery, Chiron was close to aphelion, whereas the observations showing a coma were done closer to perihelion, perhaps explaining why no cometary behavior had been seen earlier. Source: Internet
Because of the increased distance at aphelion, only 93.55% of the solar radiation from the Sun falls on a given square area of land than at perihelion. Source: Internet
Indeed, Bullialdus maintained the sun's force was attractive at aphelion and repulsive at perihelion. Source: Internet
A short History of scientific ideas to 1900, C. Singer, Oxford University Press, 1959, p. 151. (In modern heliocentric terms, this is caused by a gradual motion of the aphelion of the Earth's orbit). Source: Internet
Due to the inverse square law, the radiation at perihelion is about 106.9% the energy at aphelion. Source: Internet