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Earth has 3 Motions!! Rotation,Revolution&precession(wobble)...1)The Earth’s rotation axis traces out a circle on the sky once every 26,000 years, sweeping out a cone with an angular radius of about 23.5degree.
2)The Greek astronomer
Hipparchus (c. 146 BC) discovered this precession in the second century BC. The north celestial
pole, which marks the intersection of this rotation axis with the northern half of the celestial
sphere, now lies near the bright star Polaris..
Hipparchus (c. 146 BC) discovered this precession in the second century BC. The north celestial
pole, which marks the intersection of this rotation axis with the northern half of the celestial
sphere, now lies near the bright star Polaris..
3)However, as the result of precession, the rotational
axis will point toward another bright north star, Vega, in roughly 13,000 years. This motion of the
Earth’s rotational axis also causes a slow change in the celestial coordinates of any cosmic object
axis will point toward another bright north star, Vega, in roughly 13,000 years. This motion of the
Earth’s rotational axis also causes a slow change in the celestial coordinates of any cosmic object
4)
