For centuries, we believed that right under Earth’s liquid outer core, there existed a solid inner core of iron. However, recent studies have debunked this theory. Instead, the inner core of the Earth is mostly composed of scorching, compressed semi-soft iron.Which means the inner core of the Earth is actually not always hard, and its composition ranges from a liquid state to a solid state.
Planet's interiors undiscovered
The new research, published on 20 September in the journal Physics of the Earth and Planetary Interiors, states that the planetary ball's stiffness is said to fluctuate from hard to semi-soft to liquid metal.
Jessica Irving, a seismologist at the University of Bristol in England, told Live Science:
The more that we look at it, the more we realize it's not one boring blob of iron, We're finding a whole new hidden world.
The planet's interior remains undiscovered, as the heat and pressure are simply tremendous for any human or human-made probe to journey there.
Unless something awful happens to our planet, we will never have a direct observation of Earth's core
Earth’s CT Scan
Geophysicists have tried various methods to reach the unknown depths of the planet. They usually rely on seismic waves generated by earthquakes.
When the vibrations are measured, a scientist can figure out what’s happening inside the planet. These seismic waves or vibrations are generated by earthquakes. By measuring these massive vibrations, scientists can reconstruct a picture of the planet's inner workings.
Irking adds regarding seismic wave monitoring:
It is akin to a CT scan of a person.
The seismic waves respond in two manners—the straight-line compressional waves and undulating shear waves, explains Rhett Butler, a geophysicist at the Hawaii Institute of Geophysics and Planetology.
As it travels through the ground, each wave can accelerate, slow down, or bounce off of different mediums. When Butler carried out his routine tests, he could feel ‘something was off.’ His speculation led the scientists to take a keen interest in the subject and discover if the earth’s inner core was actually what it was believed to be.
The scientists finally discovered that, near the surface of the core, there have been pockets of liquid and ‘mushy,’ semi-solid iron, rendering the earth’s inner core to change its state of matter from time to time.
According to Butler:
We've seen evidence that not only is it not soft everywhere; it's really hard in some places. It's got hard surfaces right up against melted or mushy iron. So we're seeing a lot of detail within the inner core that we didn't see before.