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.