The core is the Earth's outermost layer. Also known as the endosphere, it is a hot mass located at the very center of the planet's interior. Its composition includes a solid inner core and a liquid outer core. The Earth's magnetic field is generated by convection currents caused by differences in material density within the core.
In this article we are going to see a complete analysis of the core of the Earth and its importance.
Origin and formation
The core originated after the planet. When Earth formed about 4.500 billion years ago , it was just a uniform ball of hot rock. It gradually underwent radioactive decay, and the heat released during the planet's formation caused it to heat up even further, to the point of melting iron. This moment when Earth reached these temperatures is called the Iron Catastrophe. The molten material within the rock, along with all the rocky material, moved at a greater and faster rate. As a result of this movement, less dense materials such as water, air, and silicates formed the Earth's mantle.
Conversely, denser and heavier materials like iron, nickel, and other heavy metals were able to pull Earth's gravity inward. This led to the formation of what we know as the Earth's first primitive core. This process is known as planetary differentiation, and it's how we begin to see that Earth is composed of different layers with distinct characteristics and compositions.
Composition of the Earth's core
As we know, the Earth's crust and mantle are rich in minerals. However, the Earth's core is composed mostly of iron and nickel metals. We also find iron-soluble materials called siderophiles. These elements are not at all common in the crust and, for this reason, have been called precious metals. These precious metals include cobalt, gold, and platinum.
Another key element found in the core is sulfur. Ninety percent of all the sulfur on Earth is located in the core. The core is known to be the hottest part of the planet. Internal structures increase in temperature with increasing depth. However, given the more than 6.000 kilometers separating the Earth's surface from the core , it is quite difficult to know the temperature of this center of molten iron and nickel. Temperatures are not constant. They fluctuate depending on pressure, the Earth's rotation, and the composition of the elements that make up the core, which is related to the geothermal gradient.
Since the convection currents are causing the materials to be moving, there are some materials that enter "new" to the core while others leave again and are no longer molten. This is due to the proximity or distance of the materials from the center and their very high melting point.
Generally, studies say that the temperature of the Earth's core ranges from approximately 4000 degrees Celsius to 6000 degrees Celsius.
Key features
Among its characteristics, we see that the materials contributing to the heat in the core are the decay of radioactive materials. Radioactive materials release a large amount of energy when they break apart. This energy is transformed into heat when it is released. The residual heat from the planet's formation is still present, heating the core. Another contributor to the heat is the heat released from the liquid outer core, which solidifies at its boundary where it meets the inner core. Recall that our planet's outer core is liquid, and the inner core is solid.
Every time we descend 1 km below the Earth's surface, the temperature increases by about 25 degrees Celsius. This means the geothermal gradient is approximately 25 degrees Celsius. The boundary between the inner and outer core is known as the Bullen discontinuity. The outermost part of the core is about 3.000 km below our feet. But the worst part is that the Earth's core is about 6.000 km deep.
To give you an idea of how little we've drilled into our planet, the deepest hole ever drilled only reached 12,3 km. It's like drilling into an apple; we've only penetrated the thin skin (and not even that).
Core layers
Let's take a closer look at the core layers.
External nucleus
It is approximately 2.200 km thick and is composed of liquid iron and nickel. Its temperature is around 5000 degrees Celsius. The liquid metal in this layer has very low viscosity, so it can be easily deformed and shaped. In this case, quite violent convection currents occur, which give rise to the Earth's magnetic field.
The hottest part of the outer core is at the Bullen discontinuity.
Inner core
It is a very hot and dense ball composed primarily of iron. The temperature reaches approximately 5200 degrees Celsius. The pressure here is almost 3,6 million atmospheres.
The temperature of the inner core is far above the melting point of iron. However, it remains solid. This is because, unlike the outer core, the atmospheric pressure is much greater, preventing it from melting. Related to this phenomenon, we can mention that the Earth's core is stationary.
With this information they will be able to know more about the core of the Earth and its characteristics.
