The Outer Core
The Earth’s structure is quite similar to an onion. It is made of four layers. Each has a different structure and plays a different role in the Earth’s geology. Two of the layers of Earth create the core.
The outer core lies about 3 thousand kilometers from the surface, and it is the only liquid layer of the Earth. That is because it’s not under enough pressure to be solid. It is made mostly of iron, nickel, with the occurrence of sulfur and oxygen. Moreover, the temperature inside is extremely high- up to 6,000°C (10,832 °F). Due to the convection of fluid ferromagnetic substances, the Earth creates a magnetic field. This, in turn, leads to a stable atmosphere and conditions for life.
The Inner Core
The innermost layers of the Earth comprise the inner core. It is probably a solid sphere with about a 1,200 kilometers radius (70% of the Moon’s radius). It is as hot as the surface of the Sun (about 5,600°C). Quite like the outer layer, it is made of iron and nickel. Interestingly, the study from 2015 suggested that the inner core has two layers. The data collected showed that the crystals in the inner layer are in an east-to-west direction. Those in the outer line up north to south. This implies a phenomenon that flipped the core’s orientation, turning the crystals in the ‘outer’ inner core. However, that hypothesis needs more studies.
We still don’t know a lot about our planet’s core. However, we can establish that its behavior is a key factor for life on our planet. First of all, the moving iron and nickel create a magnetic field. That field protects the layer from the solar wind and UV radiation. Therefore, it protects life on our planet from harmful particles. Moreover, the core’s radiating heat keeps the Earth’s surface warm. Sometimes people use that geothermal energy to warm their houses (for example, in Iceland).
Mysteries of the Earth’s Core
Earth’s layers are just a few kilometers down from us; however, we know more about the Moon than our planet’s interior. The deepest human-made core, the Kola Superdeep Borehole, reaches only 12.2 kilometers into our planet. That’s not even halfway through the lithosphere (the outermost layer)!
All studies of the Earth’s inner and outer core come from seismic data. Another unknown is the periodic reversals of the Earth’s magnetic field. Even though scientists estimated the temperatures given above, there is no way to go directly down to the core because of both the temperature and the pressure. However, the current state of knowledge is a result of numerous creative studies. Soon, one more may unravel a lot of mysteries.
Study of the Layers of Earth
In the 1940s, scientists thought that its composition is no secret. They calculated the original balance of minerals on Earth and concluded that the missing iron and nickel must be in the core. However, only 10 years later, the gravity measurements proved them wrong. The core must be heavier and denser than originally thought, though we don’t know which elements occur inside. However, that may soon be revealed.
The asteroid Psyche might be a naked iron core floating in space. The 2022 Psyche Mission may give us some answers on the structure of the Earth’s core. Moreover, it will help us compare other solid planets’ iron cores and show their most common properties.