| 单词 | periodic inequality |
| 释义 | > as lemmasperiodic inequality The older astronomers reckoned four inequalities, two common to planets and the moon, and two confined to the moon. first inequality: that which is due to the eccentricity of the orbit, and the acceleration of motion at a planet's perihelion or the moon's perigee. second inequality: that which arises from the obliquity of the direction of the planet's motion to the radius vector of its orbit; = evection n. 2a. third inequality: = variation n. (of the moon). fourth inequality: that due to the more rapid motion of the moon when the earth is in perihelion; also called annual inequality or annual equation. Later astronomers have discovered several others, as parallactic inequality (see quot. 18611); periodic inequality, the comparatively short recurring orbital perturbation due to the attraction of another body, as the great inequality of Jupiter and Saturn.extracted from inequalityn.periodic inequality periodic inequality n. Astronomy (now rare) a recurring perturbation in the orbit of a celestial object due to the gravitational attraction of another body. ΚΠ 1830 Philos. Trans. (Royal Soc.) 120 340 The periods of the periodic inequalities of all the elliptic constants due to the action of the resisting medium are fractional parts of the periodic time of the planet. 1927 Proc. National Acad. Sci. U.S.A. 13 834 The periodic inequality in the photometric formula can be accounted for by the progressive motion of the periastron. < as lemmas |
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