Earth‘s Inner Core Rotation Has Slowed, Potentially Impacting Day Length and Satellite Technology
recent seismic analyses reveal a important shift in the Earth’s inner core: its rotation has slowed, and may have paused relative to the planet’s surface. While scientists have long known the core’s rotation isn’t constant, this deceleration-observed since approximately 2009-marks a notable change with potential, though subtle, effects on our daily lives and technological systems.
The Earth’s core, a sphere primarily composed of iron and nickel, consists of a liquid outer core and a solid inner core reaching temperatures up to 5,700 degrees Celsius. Located 1,800 miles (outer core start) and 3,200 miles (inner core start) beneath the Earth’s surface, this deep interior was once believed to rotate at a stable rate. However, studies of earthquake data demonstrate fluctuations in its spin, capable of matching the speed of the Earth’s crust before appearing to stall.
This isn’t a reversal in direction, but rather a slowing of rotation relative to the Earth’s crust. The core doesn’t spin backward; it simply rotates more slowly,sometimes ceasing to change in relation to the surface. Researchers believe the Earth’s core changes its rotational direction relative to the earth’s crust approximately every 35 years, completing a full cycle of fluctuations over 70 years. The current slowdown began around 2009, following a period of more synchronized movement between the core and crust.
While imperceptible to humans, these changes can subtly alter day length by milliseconds. More considerably, the fluctuations impact precise astronomical measurements and the operation of satellites. Changes to the Earth’s magnetic field and climate are also considered possible, though the extent of these effects remains an area of ongoing research.
