The heart of our planet has been spinning unusually slowly for the past 14 years, new research confirms. And if this mysterious trend continues, it could potentially lengthen Earth's days — though the effects would likely be imperceptible to us.
Earth's inner core is a roughly moon-size chunk of solid iron and nickel that lies more than 3,000 miles (4,800 kilometers) below our feet. It is surrounded by the outer core — a superhot layer of molten metals similar to those in the inner core — which is surrounded by a more solid sea of molten rock, known as the mantle, and the crust. Although the entire planet rotates, the inner core can spin at a slightly different speed as the mantle and crust due to the viscosity of the outer core.
