perihelion

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perihelion

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(pĕr'ə-hē'lē-ən, -hēl'yən)
n., pl., -he·li·a (-hē'lē-ə, -hēl'yə).
The point nearest the sun in the orbit of a planet or other celestial body.

[Alteration of New Latin perihēlium : PERI- + Greek hēlios, sun.]

perihelial per'i·he'li·al (-hē'lē-əl, -hēl'yəl) adj.

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The point where an object in solar orbit is closest to the Sun. The perihelion distance is the distance between the object and the Sun at this point. The time of perihelion passage is the time at which an object is at perihelion.

The point in the eath's orbit when, at 147.5 million km, it is closest to the sun; on 3 or 4 January.

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Point in the elliptical orbit of a comet about the Sun in which it passes closest to the Sun.

The point in the orbit of a planet or a comet where it is nearest to the sun. The earth is at perihelion about January 1, when it is 3.4%, or about 3 million miles nearer to the sun than about July 1, when it is at aphelion—the point farthest from the sun. See aphelion.

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For a list of words related to perihelion, see:

• Celestial Phenomena and Points - perihelion: point closest to sun in orbit of member of solar system
• Fixed Positions and Points - perihelion: point in orbit of celestial body at which it is nearest to sun

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