Posted on 09/11/2005 1:45:14 PM PDT by Coleus
The giant iron ball at the center of the Earth appears to be spinning a bit faster than the rest of the planet.
The solid 1,500-mile-wide inner core, which is surrounded by fluid, rotates about one-quarter to one-half degree more than the rest of the world every year, scientists from Columbia University's Lamont-Doherty Earth Observatory and the University of Illinois at Urbana-Champaign report in today's issue of the journal Science.
The spin of the Earth's core is an important part of the engine that creates the planet's magnetic field, and researcher Xiaodong Song said he believes magnetic interaction is responsible for the different rates of spin.
The faster spin of the core was proposed in 1996 by two of the current study's authors, Paul Richards of Lamont-Doherty and Song, now an associate professor at Illinois.
The researchers studied the travel times of earthquake waves through the Earth, analyzing what are called couplets. Those are earthquakes that originate within a half-mile or so of one another but at different times.
Analyzing 30 quakes occurring in the South Atlantic and measured at 58 seismic stations in Alaska, the researchers found differences in the travel times and shape of the waves, indicating differences in the core as the waves passed through the center of the Earth.
Analyzing those differences, they calculated that the core is spinning slightly faster than the rest of the planet and is a bit lumpy.
At the faster rate, a point on the core's surface would complete an extra lap in less than 1,500 years. However, Song said in a telephone interview he thinks the rotation rate varies over long periods of time, with the core sometimes spinning slower than the rest of the planet.
"What we see right now is a snapshot of a longtime process between the
(Excerpt) Read more at nj.com ...
"A bit lumpy... oh, no wonder, I was sittin' on the cat."
Duh.
all this spinning is making me dizzy.
I thought we knew that already... I remember being told that in school.
From DC or just the planet?
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