Formation Of Earth
Our solar system did not always exist as we know it today. It may be hard to imagine now, but a few billion years ago, the solar system was nothing more than a giant rotating cloud of gas, rock, and debris are known as the Solar Nebula. Over time, the pieces of rock and debris smashed against each other, causing tremendous heat. The heat caused these pieces to melt and become welded together. They grew in size until they were large enough to develop a magnetic force of gravity. Gravity attracted more materials and gas to gather into clumps that gradually got bigger, forming the planets in our solar system, including the Earth. This continued until the area around each planet was free of debris. When two objects collide, their energy often turns into heat. This is what happened when the planets were formed. It is because of this reason that each time a meteor enters the Earth's atmosphere, the heat generated from its collision with air particles is so high that the meteor evaporates before it reaches the surface. The Earth was formed by the coming together of various materials. Some of these materials were heavier than others. Gravity pulled the heavier materials to the center to form the Earth's core. The rest of the materials formed the mantle, crust, and atmosphere.
Structure Of Earth
A long time ago, people believed the world was flat. In 1519, Ferdinand Magellan and his crew started a voyage around the Earth. Though Magellan died in 1521, his crew completed the voyage in 1552, thereby proving that the Earth was, in fact, a sphere! Ever wondered what makes the Earth in shape? The invisible force of gravity pulls the Earth into the shape of a sphere and keeps things in place on its surface. Without gravity, everything around us would have floated away into space. As the Earth rotates on its axis, it bulges around the middle, preventing it from being a perfect sphere; we do have a special word to describe it. The correct shape of the Earth is called 'geoid.' Imagine a line running through the middle of the Earth and dividing it into two halves. That imaginary lime is called the 'Equator.' It lies at an equal distance between the North and South poles.
The Earth is made up of many rocky layers is called the crust. Below the crust lies a layer of very hot, almost solid rock called the mantle. Beneath the mantle. Beneath the mantle lies the core. There are two different types of crust—continental and oceanic crust. The continental crust makes up the land on the Earth. The oceanic crust forms the ocean. The continental crust is thicker than the oceanic crust. The continental crust is eight km to 70 km thick. Most of it is made of a type of rock called granite. The oceanic crust is thinner than the continental crust. It is about eight km thick and made mainly of basalt. Did you know that the thinnest layer of the Earth is its crust? There are some areas of the Earth where the crust is so thin that hot magma (liquid) melts the rock above it and breaks through to the surface. These areas are called hot spots. The crust is divided into giant segments that fit together like a jigsaw.
These pieces are called tectonic plates. When these tectonic plates move against each other, it makes the ground shake, causing earthquakes. The Earth's mantle is divided into the lower mantle and the upper mantle. The lower mantle is found between 670 km and 2,890 km below the surface. It is made of solid rock. Even though the temperatures are hot enough to melt the rock, the pressure exerted by outer layers makes sure it stays solid. The upper mantle is found approximately 670 km below the Earth's surface. Due to extreme heat, the lower part of this layer compromises both solid and liquid rock. The upper portion is solid because of cooler temperatures. The Earth is surrounded by a layer of gases on all sides. This layer is called the atmosphere. It compromises 78% nitrogen,21% oxygen, and many other gases in smaller quantities.
Earth's Interior
The Earth's center compromises two layers, the outer core and the inner core. The outer core is the third layer of Earth (after the crust and mantle) and is made entirely of liquid. Scientists believe that the composition of the Earth's core is similar to that of iron meteorites formed in the early system. The outer core is made of liquid iron and nicked, while the inner core compromises solid iron and nickel. The outer core is responsible for the Earth's magnetic field. As the Earth spins on its axis, the iron inside the liquid outer core moves around. The movement in the liquid iron causes the development of powerful electric currents. These powerful currents cause invisible lines of force to stretch around the Earth and of kilometkilometerspace, creating a magnetic field. This magnetic field protects the Earth from harmful particles that come from the sun. The inner core forms the fourth layer of the Earth.
It is the hottest layer, with temperatures that reach incredible levels, ranging from 4,000–4,700°C ( 7,200–8,500°F). Although the inner core is boiling, it is not liquid like the outer core. The inner core is a solid metallic ball made mainly of iron. It is solid due to the pressure caused by the weight of the Earth's other three layers upon it. The Earth's inner core is as scorching hot as the sun's surface, about 5,500°C(10,000°F). That is about 6,000 times hotter than our atmosphere. That is enough heat to melt metals! Sometimes hot molten rock, called magma, bursts through the Earth's surface in the form of a volcano. When magma erupts out of a volcano under immense pressure, it is called lava. Lava appears to be almost like a stream of fire. Volcanic lava can be up to 12 times hotter than boiling water. Did you know that volcanoes can be found on land, the ocean floor, and even under ice, like those found in Iceland?
The Beginning
You must have heard of Mars being called the 'Red Planet.'Similarly, the Earth is called the 'Blue Planet.'Astronauts have exclaimed that the planet appears to be blue from outer space. Even in the dark parts, facing away from the sun, astronauts can see millions of brilliant lights, thanks to the spread of electricity! The land that we stand on his part of the solid crust on the surface of the Earth. This land above sea level only consists of about 30% of Earth's total area, called the continental crust. It is generally older and thicker as compared to the oceanic crust. The Earth has formed millions of years ago, and scientists believe that it was nothing but a ball of gases and dust floating in space. Can you imagine our planet in such a state? In fact, all the planets were formed through a gradual cooling down and solidifying of gases. Several of the planets in the solar system are still largely in a gaseous form? There are two theories regarding the formation of the Earth. One states that the materials stuck together and then separated to form the planet. The second theory states that the core was formed first, and then the different surfaces gathered around it.
Have you ever wondered how life came to exist on our planet?
One of the major reasons for this was that Earth has the optimal atmospheric conditions that helped life to flourish here. This includes the right temperature and the right mixture of gases in the atmosphere.
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