Today’s Wonder of the Day was inspired by landon. landon Wonders, “how hot is the center of the earth” Thanks for WONDERing with us, landon!
Have you ever dug a hole in the ground? Maybe you’ve planted a flower, buried secret treasure, or dug sand on a beach. People dig into Earth's surface every day for many reasons. But have you ever WONDERed just how far down the ground goes?
It’s nearly four thousand miles from the Earth’s surface to its true center. To get there, you’d have to dig through the planet’s four layers. These include the crust, mantle, outer core, and inner core.
Of these layers, only one has ever been seen with the naked eye: the crust. Like the crust on top of a pie or loaf of bread, this layer makes up the outermost part of the Earth. It contains solid rocks and minerals, including materials like coal and precious metals.
How thick is the planet’s crust? It varies. Beneath the oceans, this layer may be as thin as 3.1 miles (5 kilometers). Under land, though, it ranges from 18.6 to 43.5 miles (30-70 km) thick. Regardless, humans have never drilled deep enough into the Earth to break through its crust. The farthest people have ever drilled is 7.6 miles (12 km).
Below the crust lies the largest of Earth’s layers, called the mantle. This layer spans 1,865 miles (3,000 km) and is semi-solid. It is mostly made up of iron, magnesium, and silicon. The mantle is also where diamonds are made. Experts believe melted rock makes up the uppermost part of this layer. This allows Earth’s tectonic plates to move along it.
Finally, below the mantle lies the Earth’s core. It contains two sections: the outer and inner core. The outer core is about 1,398 miles (2,250 km) thick. It is liquid and made mostly of iron and nickel. This layer influences Earth’s magnetic field through electrical currents.
The inner core is solid and incredibly dense. Like the outer core, it contains iron and nickel. At the center of the Earth, the inner core is also extremely hot. It reaches temperatures of 9,800 °F (5,400 °C). Today, experts also believe there may be another layer—called the inner inner core. Scientists are still learning about this part of the Earth.
Are you WONDERing how experts learn about the Earth’s layers? They do so using seismic waves caused by earthquakes. By studying how these waves travel through the Earth, scientists can learn about each of the planet’s layers.
Today, experts also monitor the size and shape of the Earth’s inner core. Why? Because it’s growing! Of course, this happens at a slow rate. However, the core grows by a tiny amount each year.
By studying the inner core, scientists have also found that it’s not a perfect sphere—it’s lopsided. That’s because the inner core is growing faster on its eastern side than on its western end. Experts believe this pattern of growth has played a role in the formation of Earth’s magnetic field.
Have you ever dreamed of digging a tunnel to the other side of the Earth? If so, you now know that’s a much deeper hole than you may have imagined! The Earth's layers have formed over millions of years, and people are still learning about them today. What else would you like to learn about the ground beneath our feet?
Standards: NGSS.ESS1.C, CCRA.R.4, CCRA.L.3, CCRA.L.6, CCRA.R.10, CCRA.R.1, CCRA.SL.1, CCRA.L.1, CCRA.W.3, CCRA.L.2, CCRA.R.10, NCAS.A.1, NCAS.A.2, NCAS.A.3