Download What is the Earth Made of? Let`s review the structure of the earth

What is the Earth Made of?
Let’s review the structure of the earth. Scientists believe that the planet has five
layers. These layers are shown in the illustration above. Our earth is like an onion –
there are lots of layers underneath!
The outermost layer is the crust, which includes the continents and the ocean floors.
The crust is where we live! As you might guess from the name, the crust is very thin.
It ranges from 0 to 19 miles in thickness. The continents are the thickest parts of the
crust and the ocean floors are the thinnest.
Below the crust lies the upper mantle, which is about 415 miles thick. Next comes
the lower mantle, which is about 1,365 miles thick.
The tectonic plates are a combination of the crust and the outer mantle, also called
the lithosphere. These plates move very slowly, around a couple of inches a year.
Where the plates touch is called a fault.
Below the lower mantle lies the outer core, which is about 1,405 miles in thickness.
The outer core is made up of iron and nickel and is VERY hot (4400 to 5000+ degrees
C). This is so hot that the iron and nickel metals are liquid! The outer core is very
important to earth as it creates something called a magnetic field.
At the center of the earth is the inner core, which measures about 1,520 miles in
diameter. The Earth’s inner core is made up of iron and nickel, just like the outer core,
however, the inner core is different. The inner core is so deep within the earth that it’s
under immense pressure. So much pressure that, even though it is so hot, it is solid.
The inner core is the hottest part of the Earth, and, at over 5000 degrees C, is about as
hot as the surface of the sun.
The deepest that anyone has ever drilled into the earth is about seven miles. So how
can scientists know what lies deep within the planet?
The answer is that they use many different tools and methods. For example, they
study how seismic waves (the waves produced by earthquakes) travel through the
earth. This helps them to know the density and other properties of the different layers.