Asian Storms Push the Earth Around

Earth's axis of rotation undergoes several gyrations, such as the precession of the equinoxes, which takes about 26,000 years. Recently two of the most important axis gyrations inadvertently cancelled each other, allowing geophysicists to measure other, subtler gyrations that would normally be difficult to detect. The two larger wobbles are the 433-day cycle Chandler Wobble (whose origin is not very well known) and the wobble caused by annual weather oscillations. Their combined effect is normally to cause the rotational axis to migrate by as much as 10 meters. But from December 2005 to February 2006 their mutual nullification reduced the axis excursion to less than 1 meter. This allowed Belgian scientists to study fainter, lesser forces whose exertions could briefly be measured. The scientists saw signs of what they believe to be an influence on Earth's wobble day by day triggered by storms over Asia and northern Europe.

Lambert et al., Geophysical Research Letters, July 2006
Contact Sébastien Lambert, Royal Observatory of Belgium
Tel: +32-2-373-0312
s.lambert@oma.be