Earth's wobbleIn 1747, a paper on the discovery of Earth's wobbling motion on its axis by British astronomer, James Bradley was read at the Royal Society. For this variation, he coined the name nutation (from Latin “nutare” to nod). Bradley first noticed the fluctuation during his studies of parallax at Molyneux's observatory. Attributing it to the moon's gravitational influence, he withheld any announcement until he had observed a full cycle of the motion of the moon's nodes, taking about 18.6 years. In 1748, he was honored with the Copley Medal of the Royal Society.« |
