When the Sun freezeth over!

If you've ever sat by a bonfire on a chilly evening, you would have noticed that without constant stoking the fire would soon die out; but the great ball of fire, our sun, has been burning non-stop for over 4.5 billion years without any signs of dying out. So will it ever burn out?

Yes, it will eventually, but no need to hurry up on that intergalactic shift. The sun has enough fuel left to last another 5.5 billion years. Although the sun burns up around 700 billion tons a second, till date, it has only used up about half of its hydrogen fuel.

A day in the life of the sun.

The Sun is composed mainly of hydrogen; the rest is helium (and small quantities of other common elements like oxygen, carbon, nitrogen, silicon, magnesium, neon, iron, sulphur, aluminum, calcium, sodium, nickel and argon). Hydrogen is converted by nuclear fusion into Helium, which is also combustible (the reaction is similar to the one that happens in an H-bomb). In this way, the sun both burns and creates fuel. The sun is a very efficient furnace and over 92 percent of the hydrogen burned is converted into helium while the remaining is lost as energy in the form of heat, light and x-rays.

Our vast earth is only able to capture a miniscule percentage of this energy, the rest of which is lost to space, even then each square meter of the Earth receives 1.4 kilowatts of power each second.

Sun of a huge gun!

Our Sun, which is a yellow dwarf star, about 1.5 million kilometers across, is our closest star. It is around 150 million kilometers or 8 light-minutes away, thus light originating from the sun would take around 8 minutes to get to earth. Although the sun is composed of light gases, it weighs one million, nine thousand, eight hundred and nine billion, billion, billion kg (about 30,000 times the earth's mass) and is about 1.3 million times the earth's volume and around 1.4 million kilometres in diameter (around 100 times the earth's diameter)

At the core, the sun's temperature is about 15 million deg Celsius (27 million deg Fahrenheit), but by the time the heat reaches the surface of the sun, it has cooled down to 5800 deg Celsius (10400 deg Fahrenheit).

And God created light!

By studying other stars, which are at various stages in their life cycles, it has been determined that the sun started off as a large collapsing cloud of cold molecular Hydrogen gas and dust. Slowly over a period of millions of years, the cloud formed into a rotating disk with a huge central bulge, which further collapsing due to its large gravitational force, ended up with a temperature of several million degrees. At this temperature, the hydrogen nuclei began to fuse into helium and thus the sun's present form came into existence. At about this time, a powerful solar wind blew away the remaining gas clouds and dust, which till then had obscured the sun from view.

The beginning of the end!

What is interesting and even fascinating is the way in which the sun will perish and along with it, all life on the planet. In about a billion years, the sun will be about 10 percent brighter than what it is now, this will cause the earth’s atmosphere to dry out; wiping out most of the land-based species. 2.5 billions years later, the sun would have become 40 percent brighter than today, this would cause all the oceans to evaporate, leading to total annihilation of most life forms on earth.
Two billion years later, i.e. 5.5 billion years from now, the sun’s core would run out of hydrogen, causing it to shrink while the sun’s atmosphere will expand to about 100 times its current size; Mercury & Venus will be engulfed, and Earth will turn into a massive ball of fire although it will survive the holocaust.

The sun will then become a white dwarf, a star with a white-hot core. It would produce no energy and would be highly unstable. Slowly it would change its colour from white to yellow, then red and finally become a black dwarf, turning invisible to the naked eye. Our solar system will be altered drastically. Two of the planets will have vanished and the remaining will be frozen in complete darkness for all eternity. Although earth will survive, it is likely to have a glassy surface once all the molten rock has cooled down.

A new beginning?

It is highly probable that humans, assuming that they survive till then, would have already inhabited other planets and even galaxies, but it is improbable that earth will be able to rejuvenate itself once more and become fertile enough to host life yet again.