When you look around and see mountains, valleys, rivers, plains, don't you find it difficult to believe that milions of years ago, the earth did not even exists? In fact our sun was just another star in the solar system and it was only about 4,600 million years ago that earth and the other planets were formed around it. Do you know how this happened?
Gases and other small particles of matter first came together and clund to each other to form a cloud. Gradually this cloud became a ball. The ball began to heat up from inside melting the matter, and forming a crust on the outside. Gases ans steam from the hot liquid centre erupted to form water and the atmosphere.
Then the crust cooled and hardened and our earth came into existence. The parts of the crust lying high became the continents, and water collected in the low lying parts to form the oceans.
You know that our earth is only a very tiny part of the universe. Did you know scientists believe that the universe itself began about 13 to 18 billion years ago? According to some scientists, the Universe began with an awesome explosion that they call "The Big Bang".
What is the Continental Drift ?
You know that the continents are large masses of land. You would think that they would remain fixed in one place but the fact is that the continents are moving very, very slowly, all the time. This movement of the continents is called the Continental Drift.
It was the German scientists called Alfred Wegner who first claimed that the continents are drifting. They sometimes collide with each other to form mountains break apart in the middle. According to him the surface of the earth called the crust, is made up of rocky material. Underneath the crust lies a thick shell called the mantle, which surrounds the fiery molten heart of the earth.
Towards the centre of the earth, the rocks are like toffee and are easily deformed. This layer is called the aethenosphere. But the outer part of the earth is very hard and rigid, and it is called lithosphere. It is made up of several plates called the tectonic plates on which the continents rest. These plates are floating over aethenosphere below. and it is this movement that causes the continental drift.
How Fast are the Continents moving ?
We know that the surface of the earth is broken into large pieces or plates that are slowly shifting. The continents rest on these plates, and the speed at which they move varies from place to place. It has been calculated that continents movie at about the same speed at which your fingernails grow... About an inch every year. This may seem to be very slow but over millions of years, the continents can travel thousands of miles. In fact as a result of this movement, in 50 millions years Africa will collide with Europe, the Atlantic will be wider and Australia will move to the north!
Why can you fit South America and Africa together like a Jigsaw Puzzle?
If you look closely on the map of the world you will notice that east coast of South America fits exactly against the west coast of Africa as if they were the pieces of a Jigsaw puzzle. This is because millions of years ago, they were joined. In fact 220 million years ago all the continents were joined together to form one super continent called Pangea. There was also one Giant ocean, Panthalassa
Pangaea
In time, Pangaea split into smaller land masses, and the continents began to drift towards their present positions. In the future, the movements of the tectonic plates will cause the continents to drift even more. This will result in the Pacific Ocean shrinking, the Atlantic Ocean getting wider, and Africa splitting into two!
What happens when continents crunch together?
When continents crunch together, the edge of one continent crumples up to form high mountain ranges. The himalayas were formed in this way, and they are getting higher and higher because India is still crunching up against Asia!
Himalayan Range
In a similar manner, Africa has been pushing up into Europe over millions of years. This collision has pushed up the alps and the Pyrenees mountains!
Alps Mountain Range
Pyrenees Mountain Range
Inside of a Volcano
The area of maximum movement is around the Pacific Ocean. As the plates supporting the continents buckle and squeeze against each other, Earthquakes occur. Holes also appear in the Earth's Crust, through which molten rock is thrownout. These are the volcanoes for which this region is famous.
STAR FACTS
The Earth's Vital Statics
Diameter 12,756 km
Average Distance from the sun 149.6 million km
Orbital Speed around the Sun 29.8 km / s
Equatorial Circumference 40,076 Km
Surface Area 509,600,000 sq km
According to the Big Bang Theory. How was the Universe formed?
The Big Bang
The Big Bang theory is an effort to explain what happened at the very beginning of our universe. Scientists have no doubt that our universe did begin at a specific point in time. Before that moment, there was nothing. During and after that moment, the universe came into existence. The Big Bang theory is an effort to explain what happened during and after that moment.
Our universe is thought to have begun as an infinitesimally small, infinitely hot, and infinitely dense speck of matter. Where did it all come from? We don't know. Why did it appear? We don't know. This unimaginably small, incredibly hot little ball expanded and burst in a gigantic explosion between 10 to 20 million years ago. This Cosmic explosion hurled matter in every direction, and is called The Big Bang. Within a split second, all the forces that shape of the universe and all the forms of matter were created.
The Explosion was so immense, that material is still hurtling away in all directions at astonishing speeds. The universe created by the Big Bang continues to expand and cool to this day. We ourselves are in credible creature living on a unique planet. This beautiful planet circles a brilliant star, which is just one of the several hundred billions other stars in a galaxy soaring through the cosmos...and it all began with a Big Bang!
Will the Big screen happen again? Something that happens once can never happen again, it is true. However scientists believe it will not happen again in our Universe.
What was the Early Universe like ?
Early Universe
Scientists have a good idea of what the early universe was like, based on the laws of physics, mathematical calculations and experiments with sophisticated machines.
After the Big Bang theory say, the universe was hotter than the sun. There were no stars but rather, a searching soup of hydrogen nuclei and electrons that raced around on their own.
As space expanded the universe cooled, allowing the hydrogen nuclei to capture electron, making what is called neutral hydrogen. The early universe was opague, blocking the release of light like morning fog.
The Stars were incredibly massive, containing perhaps 200 times more material than then sun, but they will perhaps never been seen because they were born amid this cosmic fog. In time, the fog lifted, allowing the light to travel through the cosmos. The galaxies that developed during that time are so far away that they are difficult to detect.
How was soil formed?
A) Top Soil
B) Sub Soil
C) Bedrock Soil
Soil covers much of the land on earth. Do you know how it is formed.
We know that the surface layer of the earth is covered with rock. Wind, water and temperature changes will make even the hardest of rocks to crumble into tiny pieces over millions of years. The pounding seas, moving glaciers and roots of plants growing in cracks of rocks, all help in breaking them up.
Bacteria transform the bodies of almost all decaying plants and animals into soil. This matter is known as humas, and it makes the soil fertile. Earthworms and many types of insects too help to make the soil rich. The Topmost layer of soil is known as topsoil. Topsoil is rick in humas and supports plant life. The next layer is called the subsoil, and has bits of rock mixed with soil. Underneath it all is a layer called bedrock, which is rock that has not been brocken up by the elements.
Just Imagine what would happen if there were no soil? Plants would not be able to grow and without them, there would be no animals or human beings as there would be no food.
How is earth like a magnet?
Graphic showing earth's geographic and magnetic poles
Hold a compass in your hand and it will point to the earth's north pole. Why does this happen? Because the earth is like one giant magnet and the compass points to the magnetic north pole.
Why does the earth act like a magnet? We know that at the centre of the earth lies a molten metallic iron rich core. We also believe that this core is spinning. The metals in the core have many loosely bound electrons. These particles can conduct electricity. It is this mass of moving electrons which produces the magnetic field.
To best understand Earth's magnetic field, picture a bar magnet and a bunch of iron filings dumped around it. The filings form lines running from the north pole of the magnet to its south pole. The compass is acting somewhat like the iron filings and is pointing towards the north pole.
What holds things in place in space?
Have you ever wondered what holds things up in space? Why the moon or the stars do not fall down? Well, all matter in the universe, whether it is a star or a particle of dust, is held in place by four forces.
Two of them are very familiar with electromagnetic force and Gravitaional Force. You may not have heard the other two. They exist deep in the nucleus of atom. One is strong, the other is weak, and they hold the particles of every atom together
Why Dont people Fall off the Earth?
If you throw a ball up into the air. It will not keep going higher and higher until it disappears into sky. It will come back to you. This is because of a force known as Gravity.
The force of gravity is the force with which the earth, moon, or other massive body attracts an object towards itself. All objects upon earth experience a force of gravity which is directed downwards to the centre of the earth. It is a gravity which pulls things back to the surface or keeps them there... and it is gravity that keeps us from falling off the surface of the earth!
