At Home for Earth Day: Model the Earth's Layers
Use modeling clay to create a simple model of the Earth’s layered structure!
The diagram above, courtesy of NASA, shows that the Earth is composed of several layers. From the outside, in the layers of the Earth include:
Crust: the Earth’s hard outer layer, made of solid rocks. This accounts for less than 1% of our planet’s volume. There are two types of crust on Earth: the continental crust (which is under the land) and the oceanic crust (under the ocean). This is the coldest layer of the Earth because it is exposed to the atmosphere.
Mantle: Underneath the core is Earth’s mantle: an 1,800 mile (2,900 km) thick shell making up about 84% of Earth's volume. The mantle itself consists of two zones. The upper mantle starts below the crust and goes down to a depth of around 200 miles, to the boundary with the lower mantle. The lower mantle is made of magma under great pressure. It is more viscous and flows less easily than the upper mantle. The temperature of the mantle ranges from 900 degrees Fahrenheit near the crust to as high as 7000 degrees near the core.
Outer Core: The Earth’s outer core is made of liquid iron and nickel. Convection of these liquid metals creates the Earth's magnetic field—which acts as a protective shield to deflect the Sun's radioactive solar wind from hitting Earth’s surface. So, without the outer core, life on Earth might not even be possible! The outer core is about 1400 miles thick. Temperatures range from approximately 392 °F (200 degrees Celsius) at the upper boundary with the crust to approximately 7,230 °F (4,000 degrees C) at the core-mantle boundary.
For more information on the formation of the Earth’s magnetic field, see this video.
Inner Core: The inner core is a solid sphere (ball) about 70% as large as our Moon. It is believed to be made of an iron-copper alloy. We are not able to visit the Earth’s core, so its temperature can only be determined indirectly from seismic activity and computer models. Current estimates place its temperature at about 10,800 degrees Fahrenheit (6000 degrees C): as hot as the surface of the Sun!
Make Your Model
Materials:
4 colors of Play-Doh or modeling clay
Process:
Roll a ball of clay to represent the inner core
Roll flat sheets of clay and wrap them around the inner core, representing the additional layers of outer core, mantle, and crust.
When you’re finished, use a butter knife to cut your model in half and view the structure of the layers
If desired, discuss the idea of scale: do your clay layers relate to one another in similar proportions to the Earth’s real layers? Why or why not? How might you conduct this activity to create a more accurate sense of scale?
