Precession

The "wobble" of the Earth's rotational axis, which sweeps out an imaginary cone, much like a spinning top, once every 26,000 years. Precession changes the pole star as seen from Earth. Thuban, the brightest star in the constellation Draco, was the pole star while the Egyptians built the Pyramids in Egypt. Since that time, the motion of precession has rotated the Earth's axis away from Thuban and towards Polaris, the current pole star. In 13,000 years, Earth's rotational axis will point towards Vega, the new pole star.

Radio Programs

On the Move The Sun circles through the zodiac Sunday, September 6, 2015
Kochab A former pole star keeps watch Sunday, June 14, 2015
Thuban Lining up an ancient wonder Saturday, June 13, 2015
Moon in Balance Bringing a constellation into balance Sunday, May 31, 2015
Moon and Spica Eyeballing some changes in the sky Tuesday, December 16, 2014
Venus and Antares Losing a “summer” star Wednesday, October 16, 2013
Aries Moving the point of the vernal equinox Saturday, October 27, 2012
Future Beacons Lining up the North Stars Monday, July 23, 2012
Saturn and Spica Eyeballing some changes in the sky Sunday, October 30, 2011

Featured Images

Current and future pole stars
Moving On Monday, July 23, 2012

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