The interior of the earth still poses many mysteries. Researchers now want to have found evidence that the inner core of the earth is rotating more and more slowly. This could also affect the length of the day and the earth’s magnetic field. Are there also consequences on the surface of the earth to be feared?
Deep beneath our feet is its own little metal planet: the inner core of the Earth. It also rotates on its own axis, surprisingly even faster than the earth’s crust for a long time. But recently it has continued to lose speed, according to a new study published in the journal Nature Geoscience. The result: Around the year 2009, the earth’s core and crust were finally in harmony with each other.
But even after that, the Earth’s core continued to lose speed. Bad memories of the Hollywood film “The Core”, in which the core of the earth stops rotating, quickly come to life. The consequences in the film are catastrophic, since the earth’s magnetic field also comes to a standstill. In reality, however, the inner core of the earth will not completely stop rotating: The researchers rather assume that in a change of 70 years its rotation will sometimes accelerate and sometimes slow down. So everything has been there before.
The Earth’s inner core is a red-hot but solid ball of metal, mostly iron. It lies thousands of kilometers below the earth’s surface and, according to all that is known, has a diameter of around 2440 kilometers. This makes it only a third smaller than the moon. The hard core is surrounded by an outer core of liquid metal, at least that is what is assumed today. Much else about the Earth’s core remains mysterious.
The problem with exploration: Scientists have to rely on what they can indirectly learn about the Earth’s core – from the propagation of seismic waves through the Earth’s interior. These can come from natural earthquakes, but also from nuclear tests in the past. The authors of the most recent study also evaluated seismic data from earlier years. They deduced from this that the rotation of the Earth’s core slowed down in the late 1960s until it accelerated from the early 1970s. This trend has been declining again since around 2009, but according to the researchers, the rotation of the earth’s core should pick up speed again in the 2040s.
But what are the implications? There is no certainty about it. However, the research team notes that this pattern of deceleration and acceleration coincides “with changes in several other geophysical observations, particularly daylength and magnetic field,” they write in their study. With day length, which has long been increasing due to the tidal forces of the moon, tiny fluctuations could be related to the 70-year rhythm of the earth’s core. However, the effect is imperceptible to humans.
However, it is far from certain that the processes at depth are being interpreted correctly, or that there are perhaps other reasons for the readings. Another recent study, for example, suggests a much shorter six-year period in the Earth’s core’s rate of change. Another, on the other hand, sees a change in its diameter as the cause of the measurement results – according to which its rotation is not affected at all. Much of the Earth’s interior remains controversial.
(This article was first published on Tuesday, January 24, 2023.)
