Structure of the Earth
Learn about the structure of the Earth.
This lesson includes:
- two videos showing how the structure of the Earth is broken down
- two activities to aid with learning
The Earth is made up of a number of layers.
This short film describes the different layers of Earth and how they are organised.
The Earth is almost a sphere.
These are its main layers, starting with the outermost:
- crust (relatively thin and rocky)
- mantle (has the properties of a solid, but can flow very slowly)
- core (made from nickel and iron)
The core is made up of an inner and outer part.
This short film illustrates what happens when molten lava breaks through the Earth's surface.
The radius of the core is just over half the radius of the Earth.
The Earth’s atmosphere surrounds the Earth, protecting us from the Sun and providing us with the oxygen we need.
The atmosphere is a layer of gases that surround the Earth.
The percentage of each gas in the atmosphere is as follows:
78% nitrogen, N₂
21% oxygen, O₂
0.9% argon, Ar
<1% carbon dioxide, CO₂
<1% water vapour, H₂O
Water vapour and carbon dioxide are both examples of greenhouse gases and are the most abundant.
Other examples of greenhouse gas that appear in smaller quantities include methane (from animals), CFCs (from aerosols), carbon monoxide (from vehicles), nitrous oxide and ozone.
We need a certain amount of these gases because they help keep the Earth warm by trapping heat within the atmosphere (like a greenhouse).
However, if the amount of greenhouse gases increases, this means the Earth will trap more heat than is needed and can lead to global warming.
There are lots of ways to try out your science skills.
There's more to learn
Have a look at these other resources around the BBC and the web.