The Clock Is Ticking for the Earth’s Core
At the Earth’s crust, the temperatures remain relatively stable all year round. However, beneath the crust, under our feet is an incredibly hot place — the Earth’s core!
From driving plate tectonics to keeping us safe from solar radiation, the Earth’s core is not only interesting but also, in part, vital for life on Earth. But, how long can the Earth’s core stay hot?
Read on to find out.
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How hot is the center of the Earth?
How hot is the core of the Earth?
Experts believe that Earth’s core exceeds temperatures higher than the surface of the sun — over 18,032 degrees Fahrenheit (10,000 degrees Celsius).
How did it get so hot in the first place?
One theory is that around 4.5 billion years ago, our Solar System consisted of a cloud of cold dust particles This cloud of gas and dust was somehow disturbed and started to collapse, as gravity pulled everything together, forming a huge spinning disk.
The center of the disk accreted to become the Sun, and the particles in the outer rings turned into large fiery balls of gas and molten-liquid that cooled and condensed to take on solid form.
At the same time, the surface of the newly formed planet was under constant bombardment from large bodies slamming into the planet, producing immense heat in its interior, melting the cosmic dust found there.
When Earth was formed, it was a uniform ball of hot rock. Radioactive decay and leftover heat from the planet’s formation caused this ball to become even hotter. Eventually, after about 500 million years, the Earth’s temperature reached the melting point of iron—about 1,538° Celsius (2,800° Fahrenheit).
This allowed Earth’s molten, rocky material to move even more rapidly. Relatively buoyant material, such as silicates, water, and even air, stayed close to the planet’s exterior and would become the early mantle and crust. Droplets of iron, nickel, and other heavy metals gravitated to the center of Earth, forming the early core. This process is called planetary differentiation.
Unlike the mineral-rich crust and mantle, the core is thought to be made up almost entirely of metal — specifically, iron and nickel. While the inner core is thought to be a solid ball with a radius of around 760 miles (1,220 km), with a surface temperature of 5,700 K (5,430 °C; 9,800 °F); the outer core is thought to be a fluid layer of about 2,400 km (1,500 miles) thick and reaching temperatures ranging from 3,000 K (2,730 °C; 4,940 °F) to 8,000 K (7,730 °C; 13,940 °F).
The core is thought to be so hot due to the decay of radioactive elements, leftover heat from planetary formation, and heat released as the liquid outer core solidifies near its boundary with the inner core.
So, the core is incredibly hot, but just how much longer can it remain hot?
Scientists at the University of Maryland claim they will be able to answer the question within the next four years.
Driving Earth’s tectonic plate movement and powering its magnetic field requires an immense amount of power. The energy is derived from the center of the Earth, but scientists are certain the core is very, very slowly cooling off.
What makes the center of the Earth hot?
Keeping the center of the Earth hot are two sources of “fuel”: primordial energy left over from the formation of the planet and nuclear energy that exists because of natural radioactive decay.
The formation of the Earth came at a time when the solar system was brimming with energy. During its infancy, meteorites constantly bombarded the forming planet, causing excessive amounts of frictional force. At the time, Earth was rife with volcanic activity.
How long will the Earth’s core last?
Since the beginning, the planet has cooled significantly. However, residual heat from the formation of Earth remains. Although the primordial heat has largely dissipated, another form of heat continues to warm the mantle and crust of the Earth.
Naturally radioactive materials exist in large quantities deep in the Earth, with some residing around the crust. During the natural decay process of the radioactive material, heat is released.
Scientists know heat flows from Earth’s interior into space at a rate of about 44 × 1012 W (TW). What they do not know, however, is how much of the heat is primordial.
The issue is that if the Earth’s heat is predominantly primordial, then it will cool off significantly quicker. However, if the heat is created mostly in part due to radioactive decay, then the Earth’s heat will likely last much longer.
While that sounds pretty alarming, some estimates for the cooling of Earth’s core see it taking tens of billions of years, or as much as 91 billion years. That is a very long time, and in fact, the Sun will likely burn out long before the core — in around 5 billion years.
Why is the Earth’s core temperature important?
Earth’s core…