The point in the orbit of a planet, comet, or artificial satellite in solar orbit at which it is nearest to the sun. The earth is at perihelion on about 3 January. Compareaphelion.
Mathematics
Seeapse.
Astronomy
The point in an elliptical orbit around the Sun that is nearest the Sun’s centre.
Space Exploration
The point at which an object, travelling in an elliptical orbit around the Sun, is at its closest to the Sun. The point at which it is furthest from the Sun is the aphelion.
Geology and Earth Sciences
The point in the Earth’s elliptical orbit at which the planet is closest to the Sun. During the present epoch this occurs about the beginning of January, when the average amount of incident solar radiation is at a maximum. See alsoaphelion.