Chandler wobble

The Chandler wobble or Chandler variation of latitude is a small deviation in the Earth's axis of rotation relative to the solid earth,[1] which was discovered by and named after American astronomer Seth Carlo Chandler in 1891. It amounts to change of about 9 metres (30 ft) in the point at which the axis intersects the Earth's surface and has a period of 433 days.[2][3] This wobble, which is an astronomical nutation, combines with another wobble with a period of six years, so that the total polar motion varies with a period of about 7 years.

The Chandler wobble is an example of the kind of motion that can occur for a freely rotating object that is not a sphere; this is called a free nutation. Somewhat confusingly, the direction of the Earth's rotation axis relative to the stars also varies with different periods, and these motions—caused by the tidal forces of the Moon and Sun—are also called nutations, except for the slowest, which are precessions of the equinoxes.

  1. ^ e.g. Mueller, I.I. (1969). Spherical and Practical Astronomy as Applied to Geodesy. Frederick Ungar Publishing, NY, pp. 80.
  2. ^ Zinovy Malkin and Natalia Miller (2009). "Chandler wobble: two more large phase jumps revealed". Earth, Planets and Space. 62 (12): 943–947. arXiv:0908.3732. Bibcode:2010EP&S...62..943M. doi:10.5047/eps.2010.11.002. S2CID 17120582.
  3. ^ "Earth's Chandler Wobble Changed Dramatically in 2005". TechnologyReview.com. MIT Technology Review. 2009. Retrieved 23 January 2024.