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View Full Version : Why The Earth Wobbles...



DippyHippy
2004-May-17, 09:22 PM
We've known the Earth wobbles a little on it's axis as it moves through space, but recent research has said it's caused by water melting at the poles and moving down to the equator...

http://story.news.yahoo.com/news?tmpl=stor...sc/earth_wobble (http://story.news.yahoo.com/news?tmpl=story&cid=1894&ncid=1894&e=3&u=/ap/20040517/ap_on_sc/earth_wobble)

om@umr.edu
2004-May-29, 04:53 AM
The center of gravity of the Solar System is not at the center of the Sun.

This causes the Sun to wobble and must surely cause small planets like the Earth to wobble too.

With kind regards,

Oliver
http://www.umr.edu/~om

antoniseb
2004-May-29, 10:38 AM
Originally posted by om@umr.edu@May 29 2004, 04:53 AM
The center of gravity of the Solar System is not at the center of the Sun.

This causes the Sun to wobble and must surely cause small planets like the Earth to wobble too.
This is a different sort of wobble. The sun's wobble is the sort we use to search for extra-solar planets, it is a back and forth movement from its center of gravity. The Earth's part of that wobble is called its orbit.

The wobble spoken of in this article is a wobble of the axis of rotation. The article wasn't very specific about which wobble he was studying but it is fairly clear. This is beyond the well understood advancement of the equinoxes caused mostly by the tilt of the axis against the orbits of the moon and the ecliptic. It is also different from the fairly regular and well understood nutation seen in any spinning gyroscope. This is a tertiary effect wobble.

Sp1ke
2004-May-30, 12:58 AM
In the article, Blewitt says he's capable of
measuring the whole diameter of the Earth within a few millimeters using GPS technology. I thought these were only accurate to a few yards at best. Have they advanced more than that? Maybe he's using some sort of interferometry to boost the accuracy but I think a GPS system with millimeter accuracy will be in great demand.

DippyHippy
2004-May-30, 09:24 PM
Not half. The company I work for could certainly use it LOL