The structure of the earth is divided into four major components: the crust, the mantle, the outer core, and the inner core. Each layer has a unique chemical composition, physical state, and can impact life on Earth’s surface.

Starting at the center, Earth is composed of four distinct layers. They are, from deepest to shallowest, the inner core, the outer core, the mantle and the crust. Except for the crust, no one has ever explored these layers in person. In fact, the deepest humans have ever drilled is just over 12 kilometers (7.6 miles).

Scientists learn about the layers deep within the Earth’s crust by studying how seismic waves travel through the Earth. By looking at the time of arrival of the main set of waves, and how the frequencies of the waves are arranged within the set, scientists can learn about the density and other properties of the layers.

It’s the thinnest of three main layers, yet humans have never drilled all the way through it. Then, the mantle makes up a whopping 84% of the planet’s volume. At the inner core, you’d have to drill through solid iron. This would be especially difficult because there’s near-zero gravity at the core.

The strength of gravity at the center of earth is zero because there are equal amounts of matter in all directions, all exerting an equal gravitational pull. With such thick air, you eventually lose momentum and stop your yo-yo motion about the center of the earth. You end up stuck floating at the center of the earth.

Deepest drillings The Kola Superdeep Borehole on the Kola peninsula of Russia reached 12,262 metres (40,230 ft) and is the deepest penetration of the Earth’s solid surface. The German Continental Deep Drilling Program at 9.1 kilometres (5.7 mi) has shown the earth crust to be mostly porous.

Interesting Facts about the Earths Crust The crust is deepest in mountainous areas. It can be up to 70km thick here. The continental and oceanic crusts are bonded to the mantle, which we spoke about earlier, and this forms a layer called the lithosphere. This layer is cool and rock solid.

The crust is a thin but important zone where dry, hot rock from the deep Earth reacts with the water and oxygen of the surface, making new kinds of minerals and rocks. It’s also where plate-tectonic activity mixes and scrambles these new rocks and injects them with chemically active fluids.

The Earth’s Crust is like the skin of an apple. It is very thin in comparison to the other three layers. The crust is only about 3-5 miles (8 kilometers) thick under the oceans(oceanic crust) and about 25 miles (32 kilometers) thick under the continents (continental crust).

Just as the depth of the crust varies, so does its temperature. The upper crust withstands the ambient temperature of the atmosphere or ocean—hot in arid deserts and freezing in ocean trenches. Near the Moho, the temperature of the crust ranges from 200° Celsius (392° Fahrenheit) to 400° Celsius (752° Fahrenheit).