Learn what’s under your feet—one layer at a time.
Have you ever wondered what’s inside the Earth? If you could dig a hole straight down to the center of the planet, you’d pass through four main layers: the crust, mantle, outer core, and inner core. Each one is different—some are rock, some are liquid metal, and one is as hot as the sun!
This guide explains it all in a simple way—and includes fun facts and an easy classroom activity at the end.
What are the four layers of the Earth?
Earth is like a giant peach: it has a thin skin, a thick middle, and a hot, dense center. Scientists divide it into four main layers, each with its own materials, temperature, and thickness.
1. The Crust (where we live)
- What it is: The outermost layer of the Earth
- Made of: Solid rock—like granite, basalt, and soil
- Thickness: About 5 to 70 kilometers (thinner under oceans, thicker under mountains)
- Temperature: Can range from room temperature to 870°F (465°C)
This is where we live, where plants grow, and where all landforms—mountains, valleys, oceans—exist. It’s also where earthquakes and volcanoes happen.
2. The Mantle (Earth’s biggest layer)
- What it is: A thick, semi-solid layer beneath the crust
- Made of: Hot rock that can slowly flow (like silly putty)
- Thickness: About 2,900 kilometers
- Temperature: 1,800°F to 7,000°F (1,000°C to 3,900°C)
The mantle is constantly moving, which causes the tectonic plates above it to shift. This movement is what causes earthquakes and volcanoes.
3. The Outer Core (liquid metal!)
- What it is: A layer of liquid iron and nickel
- Made of: Molten metal (liquid, not solid)
- Thickness: About 2,200 kilometers
- Temperature: Up to 10,800°F (6,000°C)—similar to the sun’s surface!
This liquid layer is always moving. That motion creates Earth’s magnetic field, which protects us from harmful rays from the sun.
4. The Inner Core (Earth’s hot heart)
- What it is: A solid ball of metal at the center of the Earth
- Made of: Mostly iron and nickel
- Thickness: About 1,200 kilometers
- Temperature: Over 10,800°F (6,000°C)
Even though it’s hot enough to melt metal, the pressure is so strong that it stays solid. Without the inner core, Earth wouldn’t be the same planet we live on today.
How do we know what’s inside the Earth?
We can’t dig to the center of the Earth—scientists have only drilled about 7.5 miles deep. But we know what’s inside because of seismic waves from earthquakes. These waves move differently through solid and liquid layers, which helps scientists figure out what each layer is made of.
Fun facts about Earth’s layers
- If Earth were an apple, the crust would be thinner than the skin!
- The mantle makes up over 80% of Earth’s volume.
- The inner core spins slightly faster than the rest of the Earth.
- Earth’s magnetic field from the outer core helps protect us from solar storms.
- The deepest humans have ever drilled is the Kola Superdeep Borehole in Russia—about 7.6 miles down.
Try this: Make a model of the Earth’s layers
What you’ll need:
- A hard-boiled egg
- A knife (adult help required)
Steps:
- Cut the egg in half.
- Look at the layers:
This shows how each layer is different—and helps you remember the order!
The Earth might look simple from the surface, but it’s made of powerful and complex layers beneath our feet. From the cool crust to the blazing-hot inner core, every layer plays a role in how our planet works.
Next time you’re walking outside, just imagine—there’s over 6,000 kilometers of rock, metal, and heat between you and the very center of the Earth.
