A Chinese research team claims to have found out that the earth’s core is currently rotating in the opposite direction to the rotation of the outer core and has become slower. However, this is scientifically controversial.
Looking at the North Pole from above, the Earth rotates counter-clockwise externally. But the inner core rotates according to the new study clockwise. This is possible because the inner metallic core is surrounded by liquid rock.
There are different models for the rotation of the earth’s core
The model assumes that the rotation of the Earth’s core changes direction regularly. This can be measured by the length of the days. According to the research results from China, a period lasts around 70 years. But there are also other models in which the core of the earth stands still for a short time after less than ten years and then changes direction.
Thomas Hillebrandt from the SWR science department answers the most important questions. For everyone who remembers the film “The Core” when it was announced: The film is already 20 years old this year. But then the earth’s core stops and completely messes up the earth’s magnetic field.
Should we be worried now?
Thomas Hillebrandt: We definitely don’t have to worry. It is a wonderful, very elaborately shot trash film. And at that time it was said that the core of the earth would stop rotating, the magnetic field would collapse and all life on earth would be in danger. That will definitely not happen, we can be very sure of that.
The earth consists of different layers: crust, mantle, outer and inner core. An animation shows how thick these layers of earth are, what they are made of and what temperatures prevail in these layers.
How exactly do we have to imagine this structure of the earth and the layers of the earth?
Thomas Hillebrandt: Roughly speaking, it’s the classic image of the onion. We have this inner core. It’s solid, with a diameter of around two and a half thousand kilometers. On top of that comes the outer core, which is more liquid.
Then comes the lower mantle and the upper mantle and then the crust. Ultimately, we can say we are lucky that this structure is in place. The rotating core of the earth works like a large dynamo, creating a magnetic field that protects us from cosmic rays. In this respect it is good that the earth has this shell structure.
What exactly have the researchers found out about this rotation?
Thomas Hillebrandt: You have been looking at seismic waves coming from earthquakes over a long period of time. This is the only way to be able to illuminate the earth at this depth. After all, it is almost 6,400 kilometers to the center of the earth. They say they found that the rotation of the solid core slowed down a bit compared to the more liquid outer core.
This relative movement could also be read from a minimal – we’re talking about thousandths of a second – reduction in the rotation speed of the entire earth. So, these are the statements of these two researchers. However, there are opposing opinions that say we don’t know that much yet. The interpretation doesn’t have to be right. Well, at least there isn’t a common consensus among scientists.
How much or little do we actually know about the inner workings of our planet compared to other areas?
Thomas Hillebrandt: There is always this sentence: We know more about the universe than about our oceans. That’s the standard phrase, and it’s even more true for the interior of the earth. So just this size, so the deepest holes, where you have really pricked. We’re talking about twelve to fourteen kilometers.
As I said, it is 6,400 kilometers to the center. So the only chance of finding something out is really by analyzing seismic waves from earthquakes, which are refracted in the different layers and then travel differently, have different transit times. Science has come a long way since then. A lot has changed in the last hundred years.
But compared to what we now know about space, about the universe, it’s still a big piece of science that has yet to be done. In comparison, we know very, very little about it.