perihelion(redirected from perihelia)
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perihelion(pe-ră-hee -kee-ŏn) The point in the orbit of a planet, comet, or artificial satellite in solar orbit that is nearest the Sun. The Earth is at perihelion on or about Jan. 3. The time of year at which Earth reaches perihelion varies over a period of about 20 000 years, getting progressively later in the year. The perihelion distance q , and aphelion distance Q , of major planets and asteroids are given in Tables 1 and 3, backmatter. See also advance of the perihelion.
Perihelion(religion, spiritualism, and occult)
Although they approximate circles, every orbit is elliptical. The point in a satellite’s orbit when it is nearest the Sun is called its perihelion (from the Greek peri, meaning “near” and helios, meaning “sun”).
the point nearest the sun in the orbit of a celestial body moving around the sun in a conic section—an ellipse, parabola, or hyperbola. Because of perturbations caused by the planets, perihelion positions change. For the planet closest to the sun, Mercury, a perihelion shift has been detected that arises in accordance with the more precise law of gravitation that follows from the general theory of relativity. The distance from perihelion to the center of the sun is called the perihelion distance.