EARTH'S CORE - GEOGRAPHY

News: Earth's inner core rotating slower than surface, study suggests

 

What's in the news?

       Recent research shows that Earth's inner core, a hot Iron ball the size of Pluto, has stopped spinning faster than the planet's surface and might now be rotating slower than it.

 

Key takeaways:

       The study shows that the inner core started rotating slightly faster than the rest of the planet in the early 1970s.

       But it had been slowing down before coming in sync with Earth's rotation around 2009.

       The study said that there has been a "negative trend" since - meaning the inner core is now rotating slower than the surface.

       The researchers predicted the next change would occur in the mid-2040s.

       They said this rotation timeline roughly lines up with changes in what is called the "length of day" - small variations in the exact time it takes Earth to rotate on its axis.

 

Core:

       It is the innermost layer surrounding the earth’s center.

       The core is separated from the mantle by Guttenberg’s Discontinuity.

       It is composed mainly of Iron (Fe) and Nickel (Ni) and hence it is also called NIFE.

       The core constitutes nearly 15% of earth’s volume and 32.5% of earth’s mass.

       The core is the densest layer of the earth with its density ranges between 9.5-14.5g/cm3. 


Layers of Core:

       The Core consists of two sub-layers such as

       Inner core - Solid

       Outer core - Liquid.

 

Inner Core:

       The inner core extends from the center of the earth to 5100 km below the earth’s surface.

       The inner core is generally believed to be composed primarily of iron (80%) and some nickel (NIFE).

       The solid inner core is too hot to hold a permanent magnetic field.

       The density of the inner core ranges from 12.6 g/cm3 to 13 g/cm3.

       At 6000°C, this iron core is as hot as the Sun’s surface, but the crushing pressure caused by gravity prevents it from becoming liquid.

 

Outer Core:

       The outer core, surrounding the inner core, lies between 2900 km and 5100 km below the earth’s surface.

       The outer core is composed of Iron mixed with Nickel (NIFE) and trace amounts of lighter elements.

       The outer core is not under enough pressure to be solid, so it is liquid even though it has a composition similar to the inner core.

       The density of the outer core ranges from 9.9 g/cm3 to 12.2 g/cm3.

       The temperature of the outer core ranges from 4400 °C in the outer regions to 6000 °C near the inner core.

       Dynamo theory suggests that convection in the outer core, combined with the Coriolis effect, gives rise to Earth’s magnetic field.