Breaking News: Earth's Core Slowing Down and Reversing Direction

 Breaking News: Earth's Core Slowing Down and Reversing Direction

Deep inside the Earth, there's a big metal ball that spins all on its own, kind of like a toy top spinning inside a bigger toy top. It's a big mystery that scientists have been trying to figure out since 1936 when a seismologist named Inge Lehmann discovered it.

Scientists have been arguing for years about how this metal ball moves - how fast it spins and which way it spins. Recently, they've found some clues that suggest the ball's spin has changed a lot. But because this metal ball is so deep inside the Earth, scientists can't see it or touch it. Instead, they study how waves from big earthquakes move through the Earth to figure out what's going on.

One scientist named Dr. Lauren Waszek from Australia says that back in the 1970s and '80s, people thought the metal ball might be spinning differently. But it wasn't until the '90s that they had proof. Even then, scientists couldn't agree on what it all meant. Some said the metal ball wasn't spinning at all!

In 2023, a new idea came out that said the metal ball used to spin faster than the Earth, but now it's slowing down. For a while, they said, the metal ball was spinning at the same speed as the Earth. Scientists are still trying to figure out this big mystery.

The center of the Earth was spinning slower and slower, even going backwards compared to the layers around it. Some smart people said they needed more information to be sure, and now another group of scientists has found strong proof for this idea. A study published in a science journal on June 12 shows that the Earth's core is definitely slowing down. This backs up a theory from 2023 that the core has been speeding up and slowing down over many years.

Scientists have discovered that the Earth's inner core spins at different speeds in a 70-year cycle. Dr. John Vidale, a professor at the University of Southern California, believes that this new research settles a long-standing debate about how the inner core moves.

However, not everyone agrees that the issue is resolved. Some experts think that changes in the inner core's speed could impact Earth's magnetic field. The inner core, made of iron and nickel, is incredibly hot and sits deep within the planet.

The Earth's magnetic field influences the inner core's rotation, but other factors like gravity and the movement of the outer core and mantle also play a role. These forces cause the inner core's speed to fluctuate over time.

When the liquid metal in Earth's outer core sloshes around, it creates electrical currents that make our planet's magnetic field. This magnetic field is like a shield that protects us from harmful solar radiation. Scientists aren't exactly sure how the inner core affects the magnetic field, but they think that if the core spins slower, it could change the magnetic field and even make our days a tiny bit shorter.

Scientists use seismic waves to study what's going on deep inside the Earth. There are two main types of seismic waves: P waves and S waves. P waves can travel through anything, but S waves only move through solids or really thick liquids, like molasses. Back in the 1880s, scientists noticed that S waves from earthquakes didn't pass through the Earth's core, so they figured the core must be liquid. But then they found some P waves showing up in strange places, creating what they called a "shadow zone." A scientist named Lehmann suggested that these P waves might be bouncing off a solid inner core within the liquid outer core, based on data from a big earthquake in New Zealand in 1929.

Scientists have been studying how the Earth's inner core spins since the 1960s. They found that it goes through a cycle every 70 years. In the 1970s, the inner core was spinning faster than the rest of the planet. But by 2008, it started to slow down. From 2008 to 2023, it even started moving in the opposite direction compared to the outer mantle.

For a new study, scientists looked at seismic waves from earthquakes in the South Sandwich Islands and shock waves from old Soviet nuclear tests. By comparing the timing of these waves as they passed through the core, they confirmed the 70-year rotation cycle. According to their calculations, the core is getting ready to speed up again soon.

This study was more challenging because they only used pairs of earthquakes to measure the core's rotation. But this method also allowed them to be more precise in their measurements. If everything goes as predicted, the core will start spinning faster again in the next five to 10 years.

The seismographs showed that the Earth's core spins at different speeds over a 70-year cycle. This is something scientists like Vidale and Waszek are trying to understand. One idea is that the core might not be as solid as we thought. If it changes shape as it spins, it could affect how fast it rotates.

The team also found that the core spins at different rates depending on which way it's moving. This adds an interesting twist to the discussion, according to Waszek. However, because the core is deep underground and hard to reach, there are still uncertainties.

Even though these changes in core spin can be measured, they are so small that we wouldn't notice them in our daily lives. When the core spins slower, the Earth's mantle speeds up, making the Earth rotate faster and shortening the length of a day. But these changes are so tiny that they only make a difference of a few thousandths of a second in a day.

So, while the Earth's core is full of mysteries and potential, the changes in its spin are not something we need to worry about in our lifetimes.

Scientists are exploring the center of the Earth to figure out how it formed and how everything underneath the surface is connected. The area where the liquid outer core meets the solid inner core is especially fascinating. This boundary is a hotspot for potential activity, just like the boundaries between the core and mantle, and the mantle and crust.

There could be volcanoes at the boundary of the inner core, where solid and liquid materials are mixing and moving around. The inner core spins, which affects how the outer core moves. This spinning might help create Earth's magnetic field, but more research is needed to understand exactly how it works. Scientists still have a lot to learn about the inner core's structure.

New methods and technologies will be key to answering the many questions we have about Earth's inner core, including how it spins. Mindy Weisberger is a science writer and media producer who has written for Live Science, Scientific American, and How It Works magazine.