Inner core’s spin is debated by scientists; 70-year cycle may exist; affects length of day and magnetic field. Comment: This is an interesting story that discusses the debate among scientists about the Earth’s inner core and how it affects the planet. It is an important topic to understand as it can help us understand the habitability of other rocky planets.
In the mid-1990s, scientists discovered that Earth’s inner core, a superheated ball of iron slightly smaller than the moon, was spinning at its own pace, just a bit faster than the rest of the planet. A study published in Nature Geoscience suggests that around 2009, the core slowed its rotation to whirl in sync with the surface for a time, and is now lagging behind it. This has sparked a debate among scientists about what the mysterious metal sphere at the center of the Earth is up to.
The core is too deep to visualize directly, so scientists use seismic waves triggered by earthquakes to infer what’s happening in the planet’s innards. By comparing waves from similar earthquakes that struck the same spot over the years, the scientists were able to search for and analyze time lags and perturbations in the waves that gave them indirect information about the core.
The study examined seismic waves that traveled from the sites of earthquakes to sensors on the flip side of the planet, passing through the core on the way. The study led by Xiaodong Song, a geoscientist at Peking University, found that the core’s spin appears to be part of a 70-year cycle of the core’s spin speeding up and slowing down.
The behavior of the core may be linked to minute changes in the length of a day, though the precise details are a matter of debate. The length of a day has been growing by milliseconds over centuries because of other forces, including the moon’s pull on Earth. But ultra-precise atomic clocks have measured mysterious fluctuations that may line up with changes in the core’s rotation.
The stakes of this scientific debate are high in part because the core is a mystery that lurks, unsolved, so tantalizingly close to home. Understanding the core’s behavior may aid studies of habitability on rocky planets circling other stars. Scientists are slowly unlocking the secrets of the Earth’s mysterious hum, and this study will sharpen, not settle, the fierce scientific debate about what the inner core is up to.
This story is a fascinating look at the ongoing scientific debate about the behavior of Earth’s inner core. It is incredible to think that scientists are able to use seismic waves to infer what is happening in the planet’s innards and that the core’s behavior may be linked to changes in the length of a day. It is also interesting to consider the implications of this research for understanding the habitability of other planets. This is a great example of how science is constantly advancing our knowledge of the world around us.
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