Deep below the surface of the earth, a giant has begun to rotate in the opposite direction to that of the Earth, according to research results cited by AFP.
Earth’s core, which is about the size of Pluto, stopped spinning and then probably started moving in the opposite direction, according to research published in the journal Nature Geoscience.
The core – this “planet within a planet”, composed mainly of iron, is located about 5000 km below the Earth’s surface and moves freely in the liquid environment of its outer part.
The exact mechanism of this rotation is not known to science and is a controversial issue. Knowledge on the subject is based on analysis of seismic waves from earthquakes as they pass through the center of the planet.
After analyzing seismic wave data for the past sixty years, researchers Xiaodong Song and Yi Yang of Peking University concluded that the rotation of the core “almost stopped in 2009 before starting to reverse again.” “We think the inner core moves in one direction relative to the Earth’s surface and then another,” they told AFP. “One complete cycle (first in one direction, then in the other) takes about seventy years,” they estimate. The last spin change before the 2009 one was probably in the 1970s. According to Chinese researchers, the next cycle will occur in the mid-40s of this century.
The results of the study may shed light on the mysteries of the Earth’s depths, including the role of the inner core on the Earth’s magnetic field and on the speed of its rotation and, accordingly, on the length of the day, states the electronic publication “Nature”.
According to the two Chinese authors, there are physical connections between all layers of the Earth, BTA reported.
“We hope that our study will motivate researchers to create and test models in which the Earth is perceived and represented as an integrated dynamical system,” they explained.
Independent experts welcome the Chinese scientists’ research but have some reservations.
“This is a very careful study by excellent scientists who used a large amount of data,” John Vidal, a seismologist at the University of Southern California, told AFP. However, according to him, “none of the existing models adequately explain all the available data”.
Last year, he published research showing that the Earth’s inner core oscillates much more rapidly and changes direction roughly every six years.