nutation and Precision
Nutation
Introduction: The wobble was discovered in 1728 by the English astronomer James Bradley and released in 1748. Up to 20 years later no one knew that the cause of this extra movement of Earth's axis was the gravitational pull exerted by the Moon.
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Definition: De "Nute" means head or rock. This is the oscillation axis Earth caused by the attraction lunar, and l axis of rotation of the Earth makes around the axis of the ecliptic, a circular cone appears as an undulating path that changes the obliquity of the plane. .
Cause: That the celestial poles are approaching or moving away from the axis of the ecliptic, and to alter briefly retrogradation of the equinoxes and the movement of the celestial landscape.
Precession:
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Definition: This is a movement of the Earth and is produced by the gravitational effects of Sun and Moon on Ecuado
The precession of the equinoxes is the movement that originates in the earth and travel which is the axis of rotation of the Earth Stiene an inclination of 23 ° 27 'on the wing perpendicular to the plane of its orbit, llamdo ecliptic, the inclination Earth's axis causes the tropics and polar circles.
Equinox: time of year when the days are equal to the nights, it happens two times a year, 21 March and 23 September. that the two poles of the earth are equal distance from the sun, falling as sunlight in the hemispheres N and S.
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Solstice: time of year when the days last longer than the nights, it happens two times a year June 21 and December 21 in which the December solstice Enlighten is over the South Pole and North Pole on June anochese not at the poles during this period.
