Columbia University scientists described the situation as being virtually a planet within a planet. The outer "planet" is called Earth. The faster- spinning inner core is solid yet extremely hot iron just a bit smaller than the moon.
At a July 17, 1996 news conference, the findings were announced by Xiaodong Song and Paul Richards, both of whom are Columbia University seismologists at the Lamont-Doherty Earth Observatory, in Palisades, New York. On July 18, their discovery appeared in the scientific journal Nature.
Another journal, Science, received a submission from a Harvard University team who also found indications that the Earth's core spins independently.
The Columbia University scientists stated the inner core was moving quickly enough--between 0.4 and 1.8 degrees annually--to once every four centuries be one further lap ahead of the Earth's surface. Such a condition is not known for any other planet or rocky body in the universe. Our planet's special quality was discovered when tracking of seismic waves showed unexpected patterns.
Gary Glatzmaier, a Los Alamos [New Mexico] National Laboratory geophysicist, who had been surprised that Song and Richards could observe (via a "sonogram") the rotation, said the breakthrough was "the beginning of a new field."