章動

From Wiktionary, the free dictionary
Jump to navigation Jump to search

Chinese

[edit]
cycle of 19 tropical years motion; movement
trad. (章動)
simp. (章动)
Wikipedia has an article on:

Etymology

[edit]

So called because the principal period of terrestrial nutation, driven by the same gravitational dynamics responsible for the precession of the lunar nodes, is approximated by the length of a Metonic cycle, a calculation device that helps keeping the calendar aligned closely with both the synodic month and the tropical year. In early Chinese calendars, the concept of (zhāng) refers to the length of one such cycle, namely 19 years. Despite this connection, the Earth's nutation is conceptually distinct from that of lunar procession, and in general the periods of nutation do not conform to simple multiples or fractions of calendrical periods.

The word appears to have been coined in the translation of John Herschel's Outlines of Astronomy into Chinese by Alexander Wylie and Li Shanlan:

地軸歲差十九章動歲差十九橢圓十八十三 [Classical Chinese, trad.]
地轴岁差十九章动岁差十九椭圆十八十三 [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]
Dìzhóu chú suìchā wài, bié yǒu yáoxuán zhī dòng, shíjiǔ nián yī zhōu, míng zhāngdòng. Ruòwú suìchā, zé shíjiǔ nián zhōng, chìjí bì xíng chéng yī xiǎo tuǒyuán, chángjìng shíbā miǎo wǔ, duǎnjìng shísān miǎo qī sì. [Pinyin]
The nutation of the earth's axis is a small and slow subordinate gyratory movement, by which, if subsisting alone, the pole would describe among the stars, in a period of about nineteen years, a minute ellipsis, having its longer axis equal to 18".5, and its shorter to 13".74.

Pronunciation

[edit]

Noun

[edit]

章動

  1. (astronomy, physics) nutation

References

[edit]
  1. ^ John F.W. Herschel (1849) Outlines of Astronomy[1], 10 edition, London: Longmans, Greens, and Co., published 1893, page 207
  2. ^ 侯失勒 (1859) 偉烈亞力, 李善蘭, transl., 談天 [tántiān] (萬有文庫) (in Chinese), volume 2, 上海: 商務印書館, published 1929