The idea was first hypothesized about 70 years ago. In a bizarre repercussion of Albert Einstein's Special Theory of Relativity, objects traveling close to the speed of light appear flipped over.

This inner core has intrigued researchers since its discovery by Danish seismologist Inge Lehmann in 1936, and how it moves — its rotation speed and direction — has been at the center of a ...

But as the rotation speed is not constant, the two timescales slowly diverge. This means a “leap second” must be added every now and then to bring them back into alignment. Changes in Earth ...

which rely on accurately determining wheel speed to function optimally; tires of different diameters rotate at different speeds. Any difference in front and rear wheel speeds can be even more ...

Earth’s rotation isn’t always smooth sailing — the speed of the planet’s spin changes depending on a variety of factors, including gravitational drag from the sun and the moon, changes to ...