“nutation”的概念、定义、翻译、参考文献-科学参考

nutation

Physics

An irregular periodic oscillation of the earth’s poles. It causes an irregularity of the precessional circle traced by the celestial poles and results from the varying distances and relative directions of the sun and the moon.

Astronomy

A periodic oscillation of the Earth’s pole about its mean position on the celestial sphere, due to the attractions of the Sun and Moon on the Earth’s equatorial bulge. It causes a small periodic variation in the positions of stars, and is superimposed on the much larger effect of precession. The main oscillation has an amplitude of about ±9″ and a period of 18.6 years, equal to the revolution period of the Moon’s nodes around the ecliptic. In addition there are many smaller oscillations, some with periods as small as a few days. Nutation is conventionally resolved into nutation in longitude and nutation in obliquity, which are respectively parallel and perpendicular to the ecliptic.

Biology

The spiral movement of a plant organ during growth, also known as circumnutation. It is seen in climbing plants and helps the plant find a suitable support to twine around. Examples are the coiling movements of the shoot tips of runner beans and of the tendrils of sweet peas.

Geology and Earth Sciences

Irregularities in the orbital motion of the Earth (or other planets) superimposed on the precession of its axis. The dominant nutation of the Earth’s axis has an 18.6-year periodicity.

单词	nutation
释义	nutation Physics An irregular periodic oscillation of the earth’s poles. It causes an irregularity of the precessional circle traced by the celestial poles and results from the varying distances and relative directions of the sun and the moon. Astronomy A periodic oscillation of the Earth’s pole about its mean position on the celestial sphere, due to the attractions of the Sun and Moon on the Earth’s equatorial bulge. It causes a small periodic variation in the positions of stars, and is superimposed on the much larger effect of precession. The main oscillation has an amplitude of about ±9″ and a period of 18.6 years, equal to the revolution period of the Moon’s nodes around the ecliptic. In addition there are many smaller oscillations, some with periods as small as a few days. Nutation is conventionally resolved into nutation in longitude and nutation in obliquity, which are respectively parallel and perpendicular to the ecliptic. Biology The spiral movement of a plant organ during growth, also known as circumnutation. It is seen in climbing plants and helps the plant find a suitable support to twine around. Examples are the coiling movements of the shoot tips of runner beans and of the tendrils of sweet peas. Geology and Earth Sciences Irregularities in the orbital motion of the Earth (or other planets) superimposed on the precession of its axis. The dominant nutation of the Earth’s axis has an 18.6-year periodicity.
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