Notes For Alien
Here are your notes about the Earth
The crust is a layer of rock that is the Earth's outer skin. Earth's crust is very thin. It is only 50 km deep. There are two parts to the crust, the oceanic and the continental crust. The oceanic crust lies beneath the ocean. The continental crust is the crust that forms the continents. We humans live on this part of Earth. The main elements in the Earth's crust is oxygen and silicon.
The mantle is the second layer of the Earth. It is a hot layer of rock that is still solid. It forms the main part of the Earth. The mantle is 2,900 km deep. The temperature of the mantle can reach up to 4,000 *C. That's hot! There is 3 layers in the mantle. The lithosphere is the upper layer of the mantle and the crust. The second layer is the asthenosphere. The asthenosphere is a softer layer, but it is still solid, you could bend it like metal. The last layer is the Mesosphere.
Earth's Outer Core
The Earth's outer core's temperature can reach up to 5,000 *C. It has a depth of 2,258 km. This layer consists liquid iron, nickel, (scientists say) oxygen, sulfur and silicon. It surrounds the inner core. This core is a liquid.
Earth's Inner Core
The inner core has a temperature of 6,000 *C. That is the same temperature as the surface of the Sun. The depth of this core is 1,250 km deep. Unlike the outer core, the inner core is a solid ball of metal. This ball consists iron, nickel, (scientist say) oxygen, sulfur, and silicon.
How Did We Find Out About These Layers?
Geologists our our answer. Geologist have been studying the Earth for a long time. They use two main types of evidence to study the layers of the earth. One type is direct evidence from rock samples, the second one they use is indirect evidence from seismic waves. Seismic waves are produced when earthquakes occur.
Pressure- The force pushing on a surface divided by the area of that surface.
Basalt- A dark, dense, igneous rock with a fine texture, found in oceanic crust.
Granite- A usually light-colored igneous rock that is found in continental crust.