Earth’s inner core has slowed—and is now rotating in reverse. Here's what scientists just discovered. Earth's inner core—an iron-rich sphere roughly the size of the Moon—is doing something remarkable: it’s not just slowing down, it’s now rotating in reverse relative to the surface. According to new research tracking seismic waves from hundreds of earthquakes, the core has shifted from spinning slightly faster than the rest of the planet to gradually decelerating since around 2010. Now, it appears to be moving in the opposite direction, beginning a new phase in a roughly 70-year cycle of motion deep beneath our feet. While this reversal sounds dramatic, scientists stress there’s no danger to life on the surface. However, the subtle shift may affect Earth's magnetic field and slightly shorten the length of our days by fractions of a second. More importantly, it gives scientists a rare window into one of Earth’s most inaccessible regions. The inner core plays a key role in generating the planet’s magnetic shield and may influence geologic activity. The discovery that it behaves more like a dynamic system—shifting, rotating, and possibly changing shape—suggests there's still much to learn about the hidden machinery at Earth’s center. Source: Guyer, J. Earth’s core has slowed so much it’s moving backward, scientists confirm. Here’s what it could mean. CNN Science

Earth’s inner core has slowed—and is now rotating in reverse. Here's what scientists just discovered. Earth's inner core—an iron-rich sphere roughly the size of the Moon—is doing something remarkable: it’s not just slowing down, it’s now rotating in reverse relative to the surface. According to new research tracking seismic waves from hundreds of earthquakes, the core has shifted from spinning slightly faster than the rest of the planet to gradually decelerating since around 2010. Now, it appears to be moving in the opposite direction, beginning a new phase in a roughly 70-year cycle of motion deep beneath our feet. While this reversal sounds dramatic, scientists stress there’s no danger to life on the surface. However, the subtle shift may affect Earth's magnetic field and slightly shorten the length of our days by fractions of a second. More importantly, it gives scientists a rare window into one of Earth’s most inaccessible regions. The inner core plays a key role in generating the planet’s magnetic shield and may influence geologic activity. The discovery that it behaves more like a dynamic system—shifting, rotating, and possibly changing shape—suggests there's still much to learn about the hidden machinery at Earth’s center. Source: Guyer, J. Earth’s core has slowed so much it’s moving backward, scientists confirm. Here’s what it could mean. CNN Science