evection

American  

[ih-vek-shuhn] / ɪˈvɛk ʃən /

noun

Astronomy.

1. a periodic irregularity in the moon's motion, caused by the attraction of the sun.

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evection British  

/ ɪˈvɛkʃən /

noun

1. irregularity in the moon's motion caused by perturbations of the sun and planets

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Other Word Forms

• evectional adjective

Etymology

Origin of evection

1650–60; < Latin ēvectiōn- (stem of ēvectiō ) a going upwards, flight, equivalent to ēvect ( us ) (past participle of ēvehere to carry forth, move forth) + -iōn- -ion

Example Sentences

Their orbits would have expanded slowly for billions of years until the radius of the more distant one’s orbit was 8.3 times that of Saturn—at which point it would have entered a powerful evection and started swinging around like a wild thing.

From Economist

Dr Cuk’s explanation relies on another form of orbital perturbation called an evection.

From Economist

Here his mathematical powers are at their best, and he made a discovery of an inequality in the moon's motion known as the evection.

From Project Gutenberg

In astronomy, besides his capital discovery of the precession of the equinoxes just mentioned, he also determined the first inequality of the moon, the equation of the centre, and all but anticipated Ptolemy in the discovery of the evection.

From Project Gutenberg

His chief discovery was an irregularity of the lunar motion, called the ‘evection.’

From Project Gutenberg