单词 | parallactic inequality |
释义 | > as lemmasparallactic 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.parallactic inequality parallactic inequality n. an inequality in the moon's orbit caused by the gravitational attraction of the sun, in which the moon in its first quarter is ahead of its position as calculated assuming uniform motion, and in its last quarter lags behind the calculated position. ΚΠ 1831 Philos. Trans. (Royal Soc.) 121 233 (note) Parallactic inequality. 1861 G. F. Chambers Handbk. Descr. Astron. i. vii. 43 The Parallactic Inequality, which arises from the difference in the influence of the Sun's attraction when the Moon traverses that part of its orbit nearest the Sun. 1974 Proc. Royal Soc. A. 338 406 The Society desired Newton to determine the solar parallax from the parallactic inequality of the Moon's motion. < as lemmas |
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