A Gravitational Battle Within the Earth Is Changing the Length of Days
Earth's days are not exactly the same length. Scientists have been recording small variations in for decades. These changes are minuscule—sometimes just a few milliseconds—and mostly imperceptible, but scientists are keen to understand them as they point to a much more monumental change: Our planet’s rotation speed is shifting.
Scientists have already pinpointed a handful of compounding causes. Fluctuations in the atmosphere and oceans can slightly speed up or slow down the Earth’s rotation; major earthquakes can redistribute part of the planet’s mass; and by depositing enormous amounts of water into the oceans, melting continental ice is also a factor.
These influences account for some of the more sudden and recent changes, but on a several decades-long timescale, some of the variation appears to originate from a source much deeper within the Earth. Beneath our planet’s rocky mantlelies the outer core—a 1,400 mile thick layer of ultra-hot liquid metal...
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