Page:Illustrated Astronomy.pdf/50

 DID YOU KNOW THAT…

''...the spatial mission InSight landed on Mars on November, 26th in 2018, and its target is observing the insides of the planet? To do so, it is digging a couple of centimeters, and it is placing a seismometer that helps to understand better the Martian crust, mantle, and core, and how heat escapes onto its surface.''

Based on these discoveries, we hope to understand better how rocky planets evolve.

LAYERS OF EARTH

Thanks to researches that the Danish seismologist Inge Lehmann carried out is that today we know our planet has a core, and it can be divided into two parts: inner and outer core.

The first one is solid. It has a temperature around 5,400 °C, similar to the solar surface’s, and is primarily made up of iron and nickel, while the outer core is made up of molten metal, and apparently rotates differently from the outer layers, which makes it responsible for the Earth’s magnetic field.

Then, looking from inside out is the mantle, a layer where most of the Earth’s mass is concentrated (about 67 %) and corresponds to 84 % of its total volume. In there, the most considerable part of both seismic and volcanic activity happens. In some cases, during the collision of plates, an element of the material in the upper mantle and the oceanic crust raise, allowing us to have access to rocks that belong to the mantle. These places, which are crucial to understanding the composition of the upper Earth’s mantle, are called ophiolites. We have one in Chile, and its location is in Patagonia, specifically at the Taitao Peninsula.

Finally, the outermost layer is known as the crust. It is very thin. It measures between 5 and 7 km deep, and all human and animal activities developed on it.

The most of the rocks, part of the Earth’s crust, are about 100 million years old, but it has been found some minerals 4,000 million years old, which would show that the Earth has a rigid crust almost since its formation. 50 • • •