Oh ! Dear Gold !

The cosmos never fail in conspiring different ways to amaze us and make us wonder about its different beautiful aspects.

A nebula - the blue lights are the stars that are forming

About 13.5 billion years ago, when our universe didn't take shape that we observe today, there was only gaseous Hydrogen of a nebula from which it was formed. Hydrogen is lightest of all the elements that can be found anywhere. These atoms of hydrogen, or the tiny mass-points, were pulled together by gravity - a force that manifests itself fully with increasing mass. These clusters of mass-points produced hydrogen-clouds. Gradually with increasing conglomeration of more Hydrogen atoms; the gravity increased followed by rise in temperature. The process repeats itself time and again until a massive central core is formed with high density and temperature. The energy of the particles that are pushed towards the centre of the nebula gets converted into heat energy, thereby, increasing the temperature of the core of the nebula. Finally, a temperature of about 10million degrees is reached; when accidentally by the process of nuclear fusion, the Hydrogen at the core gets converted into the next heavier element - Helium. This nuclear reaction is followed by further rise in temperature and the energy is radiated in the form of heat and light. This is how a star is born. This is a thousand times bigger than our sun and is deep blue in colour.

The star that is born

Helium being heavier than Hydrogen sinks down to the centre of the star, the layers of Hydrogen outside the core provides the fuel required to continue the nuclear fusion process at the centre. These hydrogen-clouds are  further used up by the core to produce more Helium and the process is repeated time and again. The mass of the core increases, gravitational pull increases, further increasing the temperature. At such a high temperature, the Helium atoms fuse together forming heavier elements like Carbon(a vital element found in every living thing) and Oxygen. This process of fusion goes on repeating to produce different elements of heavier mass and finally Iron is formed. Now, this iron cannot undergo any fusion reaction further to produce heavier elements. The star which was increasing in size and temperature becomes gigantic and glows with a red colour. This is then called a Red Giant.

Red giant

While the gravitational forces tend to contract the star, the energy released by nuclear fusion taking place at the centre; pushes the matter out. An equilibrium is reached when these two opposing forces balance each other. Then the size of the star remains constant for almost a few billion years.

At a time when all the surrounding Hydrogen  are used up in the core and the star is mostly made of Iron, the nuclear furnace at the centre stops and the equilibrium is lost. Gravity now takes over - squashing all the Iron and other elements that were produced at the centre. This process is accompanied by increase in density as well as rise in temperature to about 100 times the core of our sun! Finally the star collapses and explodes, giving out enormous amount of light - a process called 'death of the star'. The exploding star throwing out large amount of matter and light in the space is a visual treat and is called a Supernova. 

                      Hubble Space Telescope image showing Supernova 1994D in galaxy NGC 4526

From the remnants of this explosion some of the most valued elements are formed! This explosion, for a brief microsecond, forces the Iron to fuse to produce heavier elements - like Gold, Platinum, Lead. So in a way, they are forged in the heart of an exploding star at its time of death!

A chunk of Gold

So, if you have a gold ring; make sure you appreciate it. The metal was built in a blinding flash of light billions of years ago!

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 .

                                       Our planet - Earth , as it looks from the outer space

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.

                                      The Rosette Nebula : Each tiny spot of light is a 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 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.

                                                                       Our Solar system

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.

                                                               Different layers of Earth

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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