By Joby Warrick
Washington Post Staff Writer
Monday, February 2, 1998; Page A02

Love may make the world go round, but it's the oceans that make it wobble like a top.

So concludes a new study that examines why Earth's pole of rotation wiggles slightly in relation to its crust. Scientists have long suspected that wind currents and land distribution contribute to the planet's gyrations, but research by three Massachusetts scientists suggests that water also plays a major role.

The researchers used computer models to show how the oceans literally push Earth around, albeit slightly. Seas press against continents, for example, and large ocean currents rub against each other in a way that creates a slight drag in Earth's rotation, lead researcher Rui M. Ponte of Atmospheric and Environmental Research Inc. reports in the Jan. 29 issue of Nature.

The end result is a tiny wobble at the poles -- a shift of several yards -- that varies according to a seasonal cycle. This wiggling isn't noticeable to most of us, although major shifts in polar rotation over eons is suspected to play a role in climactic changes.

While the new finding greatly improves scientists' understanding of polar wobble, Ponte is still searching for a "missing power," in addition to wind and water. The mysterious force could be huge amounts of groundwater stored in Earth's crust, he says -- or it could simply be that scientists' calculations are slightly off.