攝動

Coined by Alexander Wylie and Li Shanlan in 1859 as a calque of English perturbation in their translation of John Herschel's Outlines of Astronomy:

前數卷屢言，月與行星于刻白爾所定三例外，尚有小差，名曰攝動。 [Classical Chinese, trad.]

---

前数卷屡言，月与行星于刻白尔所定三例外，尚有小差，名曰摄动。 [Classical Chinese, simp.]

From: John Herschel (侯失勒約翰), 1849. Outlines of Astronomy, Chapter 5. Translated into the Chinese by Alexander Wylie (偉烈亞力) and Li Shanlan (李善蘭) as《談天》in 1859.[1][2]

Qián shù juàn lǚ yán, yuè yǔ xíngxīng yú Kèbái'ěr suǒdìng sānlì wài, shàngyǒu xiǎochā, míngyuē shèdòng. [Pinyin]

In the progress of this work, we have more than once called the reader's attention to the existence of inequalities in the lunar and planetary motions not included in the expression of Kepler's laws, but in some sort supplementary to them, and of an order so far subordinate to those leading features of the celestial movements. These inequalities are known, in physical astronomy, by the name of perturbations.

攝動

1. (astronomy, physics, of orbital motion under gravitation) perturbation