Space Exploration
Why are we here? Where do we come from? These are some of the most intriguing questions that has always fascinated human mind. It's an essential part of human nature to find answers to such questions. Though we can trace our ancestry back to hundreds of thousands of years - the dawn of humankind, but in reality our story extends far - further back in time - to the beginning of the universe.
The story of creation of this universe is the story of creation of man.
So, its story , is our story .
The Earth was formed about 4.5 billion years ago along with our solar system.In space randomly drifting molecules of gases (mostly Hydrogen) and dust collect together to form a cloud of colourful splashes in the darkness of the space.This is called a Nebula. The gravitational forces of attraction (due to their masses) helps in contraction of these particles - thereby increasing the temperature and density at the core. When the temperature of the core reaches 10∧7 Kelvin, nuclear fusion (the process of joining together of lighter molecules of elements , releasing vast amount of energy) begins.In this fusion reaction, Hydrogen gets converted into Helium. The large amount of energy released continuously by the starting of the nuclear furnace appears as light. This is called a star.
So, in this way stars are formed from the Nebulae.. and our Sun is one such star.
A component of the universe that has a huge group of stars and other celestial bodies bound togther by gravity is called a galaxy. There are over 100 billion galaxies and our sun is one of the ordinary-sized star belonging to the Milky Way galaxy.
The structure of the Earth is deduced from the study of Seismic waves. It was found that our Earth was formed along with other objects of the solar system, some 4.5 billion years ago. The solar system was formed from a cloud of gases and dust particles that contracted to form a spinning disk at whose centre the sun was formed. In the solar system, the sun is the most massive object and around it the dust and gases got cooled forming particles that collected to form the planets, asteroids, moons etc.
Due to the kinetic energy of the constituent particles, the energy released in radioactive decays and their contraction under gravity, the Earth got heated and melted about 800 million years after its formation.
The heavier elements like Iron and Nickel sank to form the liquid core . The outer layer got cooled over time and solidified to form the crust. In between them, a semiliquid mantle was formed. What we see coming out from volcanoes are these inner core materials that come out through some opening on the Earth's crust.
But how does the gravity comes into existence?
How life started on this planet?
These are some of the questions that fascinates the human mind - the answers are still to be found out exactly. There are many theories , controversies and loopholes in explaining these fundamental questions. Some of these will be dealt in my subsequent articles.
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