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ften Astronomy is about looking up in the sky, but now, in this post, let's travel to Earth's center. Meaning deep down until we reach its core. Hello and welcome to our Blog called CosmicWisdom, where we talk and know about celestial bodies, their mechanisms, and other features in very simple language, without any jargon.
Introduction:
As many of us know, that Scientists mainly divide the Earth's interior into 3 distinct parts called the crust, Mantle and Core. In this post, we'll talk about their physical properties and clear up some confusion spread among commoners and non-experts. Also, you'll read it in a way like you are travelling right inside the ground from where you stand, until you reach the core. Without wasting any time, let's commence our journey. Let's look at this CGI Image prepared with our GPU and Blender. Although there's a compression artifact, it shows the true geometry of the underground.
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| Interior of The Earth |
Crust:
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| A simplified view of underground with some activities |
Let's look at this CGI Image prepared with our GPU and Blender. Although there's a compression artifact, it shows the true geometry of the underground.
This is the outermost layer of the earth, which we call simply the ground, soil, sand, or oceans. Actually, these are on the crust. Just like an apple has three distinct layers, its rind, then the thickest fleshy mesocarp, and then the central chamber for seeds.
We also see sometimes Apple's rind might have some scratches, pits, bumps, folds, and sometimes only limited to the outermost layer. Our Earth's crust acts as the same layer. In this case, where the continents are located especially the mountainous regions, this layer could be 70-100 km thick, whereas in the oceans it is 5-10 km.
The continental or Islandic grounds are mainly the bumps of the crust, around mountains, where this bump is more pronounced.
If you've heard a certain mountain peak is 5000 meters, then this doesn't mean this summit would be really 5000 m from the mountain's foot; instead, it's mainly the vertical distance from the sea surface to the summit. The tallest summits, like Everest, are actually mountains on the mountain, meaning they already sit on very high ground elevation.
We stand on a pile of silicon compounds, like silica, silicate, and others. We walk on it, we see its rocks, soil, sand, Lava. We build our homes and infrastructure with concrete, all of which are different forms of Silicon. This silicon is the most abundant element on Earth after Nitrogen (in the atmosphere) and Oxygen. Too much silicon on Earth, rocky planets, asteroids, meteoroids and other rocky bodies in our solar system.
This observation suggests our solar system formed in the Silicon rich Nebula, an aftermath of the supernova explosion of a massive star.
Well, let's move to inside the ground, in the ground you'll first meet the soil, some stones, and other dust, it's pretty simple, and everybody knows. If you keep moving deep inside the ground, you'll feel that the temperature is increasing at a certain depth, and the pressure also shows an effect. That's why our drilling robots struggle to dig in the ground when they reach about 15 km depth.
Also, remember you've fathomed only the Rind-like thin layer of the apple, while this earth-like apple has a radius of around 6400 km, how much we've dug? Only 15-20 km, while there is a large portion like a country to dig in. That's why we're comparing the earth with an apple, which has a very thin outer layer and a large mesocarp.
You'll also see that Soil and dust are mainly found in the upper layers, and then the crust is mainly solid rock, with different sizes. The cracked ones as well, because all these upper layers are supported by Tectonic plates.
Keep in mind that Tectonic plates are responsible for Continents and landmass topologies, earthquakes and some volcanic activities. It's pretty simple if you shake the basal zones, the upper layers will definitely respond; that's the mechanism of earthquakes and Landslides.
In the case of landslides, the cavities, soft rocks, or even soil, or in response to an earthquake in other places, the inner rocks may relocate, causing mountain formations, seas, valleys, and other land features.
Sometimes, the entire tectonic plates can move due to various factors, and this causes continents or island drifts. Let's explore some of the Geographical incidents:
- The place where the Himalaya mountain range is located, there was once a sea, but Earth's crust reshaped it, and it caused the highest land elevations. As a result, the tallest mountain summits like Everest or K2 are there. Some sea creature fossils are found there, which is amazing, isn't it?
- According to experts, the portion around Madagascar, Saudi Arabia's southwestern and Africa's eastern seas, was once land, but now we see waters there.
- The Caspian Sea used to be a land or plain, but it's one of the results of land reshaping.
- In the past, the West African and Eastern South American landmass was almost one, but because of continental drift, if you look at the world's map, you can easily say they might have been in one piece.
- Like the previous one, the modern India and the Australian continent were connected, but now look separated because of drift.
Let's now see what causes those tectonic plates to move, so that the valley becomes mountains, mountains become seas, and land or sea sometimes disappear, or entire continents move.
Its answer is buried even deeper than the tectonic plates or the innermost crust layers. Let's descend into more depth.
Mantle:
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| The Mantle layer activities |
This is the layer beneath the crust, it's the thickest one and mainly remains silent, but its effect decides the fate of a mountain or Sea, let's see how. In the last section, we talked about the movement of Tectonic plates and layers. The part where the crust and upper mantle layers meet is mainly a transition of temperature and pressure, whereas the rocks might look similar.
The mantle rocks are super solid, but due to extreme temperature and pressure, they move or reshape like chewing gum. But this motion is really slow, only a few centimeters per year. That's the paradox that happens, on one side we say it's a super solid rock, whereas it ripples or changes its shape like a slow amoeba or chewing gum.
This is the layer where the lava forms, since none of the earth layer is mainly homogeneous; temperature and pressure constantly move to keep the layer at a similar temperature. That's why the temperature and pressure difference happen.
If you have read our previous posts, you might know that Temperature is basically the movement of subatomic particles; the hotter particles rise and lose heat. Once they lose it in a certain point range, then they don't rise further. If this movement occurs in a group of molecules or atoms, which always happens, we call it convection.
Since everything is made by assembling those subatomic particles, including the mantle layers. The temperature and pressure cause this convective movement in this super-solid rock. Similar processes, like the boiling of water or fluids, are also caused by convective movement of particles. But in the mantle, this happens in rock, which is why the tectonic plates and crust layers have no stable base. This makes Earth's upper layer constantly changing and reshaping, but we should consider ourselves lucky that this process is too slow and takes thousands of years to move islands or cause continental drift.
This also means the mantle rocks can break the crusts and can break apart the tectonic plates, which means more pieces to independently move.
Why Lava always rises?
As you know, some mantle rocks can reach a critical temperature at which they cannot remain truly solid and act like fluid; this requires specific conditions, though.
According to the laws of nature, things move from higher to lower gradients. meaning, if you pour water into a plastic cushion, press a certain part with your hand, you'll see that water will flow to low-pressure zones if there is enough blank space or the cushion can handle; otherwise, it will burst. The same high-to-low movement exists in many things like temperature, pressure, potential, etc.
As we said that mantle already feels tremendous pressure, so the Lava is fluid; it has only one way to escape, which is toward lower-pressure zones, which is upwards from the center of the Earth, because temperature and pressure increase with depth if we move towards the core.
Let's now move beneath the mantle.
Core:
The Earth's central part has two distinct zones. The outer layer is basically Molten Iron that flows and boils, since Iron is conductive, Earth's daily rotation grants it magnetic influence, and the movement of this fluid and Earth's rotation forms a powerful magnetic field. Before we know about it, let's clear up confusion that this fluid is not Lava, it may look like that way, but Original Lava is mainly Molten silicate and other compounds, whereas the outer core's fluid is molten Iron basically.
The inner core is solid, however and it is a mixture of metals like Aluminum and Iron. Why? Because around the outer regions of the Core, the pressure and temperature are very high and turn the hard metals into fluid, but in the inner regions, the pressure and temperature are even higher, which blocks the movement of subatomic particles of the Iron-Nickel ball, hence it's a super solid ball.
The inner core behaves like a large ball magnet. The North Pole lies in Earth's South pole whereas its South Pole points toward Earth's North. This kind of cross arrangement is useful for Long time Magnetisms.
Now, we talked about Earth's Geographic pole and Magnetic poles. The geographic poles don't change unless the Earth itself flips; they are absolute +90 (North) -90 (South) degrees latitudes, whereas the magnetic poles do move. Some decades ago, the Earth's South magnetic pole (North Geographic) was around Canada, but it's slowly moving toward the common direction of Russia.
Geographic poles, such as points in the Arctic Ocean and Antarctica, have nothing to do with Earth's magnetism; all credit goes to Magnetic poles. Thousands of kilometers beneath our feet, there is a giant magnetic sphere. Like all magnets, it creates an influence zone where charged particles like electrons, protons, or ions move in a coordinated fashion; some are distracted, deflect or join their movements. This influence zone is called the magnetic field.
The Earth's magnetic field doesn't let most of the Solar wind (stream of protons, electrons, ions) particles enter the atmosphere, due to its magnetic influence field. If this invisible field were not present, then the Earth's atmosphere, chemical composition and features like clouds, water, etc. would not last longer because those charged particles can break their chemical bonds. The magnetic field is also one of the entities that is responsible for life on Earth
If you wanna read more about how the Dangerous Cosmos or Solar wind is, you can look at our other posts, like WR Stars, Stellar wind mechanism and others, where we've been able to provide some more detail.
That's all for today, see you in another post.