U of I Geologists

As the earth turns, the center of the earth turns even faster.

Confirming assertions first made in 1996, a team of geophysicists are presenting data in the journal Science today showing that the earth's inner core, a ball of solid iron larger than the moon, spins faster than the rest of the planet. Over a period of 700 to 1,200 years, the inner core appears to make one full extra spin.

That extra spin could give scientists information about how the earth generates its magnetic field.

The inner core, 1,500 miles wide, sits at the center of the planet, ensconced in a sea of hot liquid metal known as the outer core. With nothing to hold it in place, the inner core can rotate independently. Nearly a decade ago, two scientists at the Lamont-Doherty Earth Observatory of Columbia University said it did just that.

Other scientists, however, questioned the analysis, which was based on the speed of earthquake waves passing through the earth. Subsequent attempts to pin down the inner core's rate of spinning produced a wide range of answers. Some said it spun, but at a much slower rate than the Columbia scientists claimed. Others said they could find no sign that the core was out of step with the other parts of the planet. Some said it seemed to be spinning at a slower rate, not faster.

The same researchers who made the original claim, Paul G. Richards and Xiaodong Song, now a professor of geology at the University of Illinois, led the new research, which they said should remove any remaining doubts.

While it does not precisely pin down how much more quickly the core is spinning, Dr. Song said, "what this particular paper shows is it cannot be zero."

The New York Times