Its starting to get really hot here in Australia. I cannot handle the heat - have lived here over 8 years now and still have not acclimatised... i'm not a fan of the summer in all honesty, most people think I am mad - their not far wrong :)
So, after this boiling sweaty day, it got me thinking about one of my favourite subjects Astronomy. It amazes me that there are some people out there that still do not realise that our Sun is a star, seriously, but this is not their fault, maybe they didn't do physics at school, maybe they didn't go to school, maybe they didn't care or maybe just were not taught it. It really doesn't matter why they don't know, but, I really think that a good understanding of our Sun and the fact that it is already middle aged, may give people a better appreciation of how lucky we are to be at the right distance away from, to us, a perfect sized star. Anyway, I am going to share with you, in brief, how these billions of stars out there are made and what happens once they have used up all their energy. I hope you find it as amazing as I do, if not amazing, I hope it makes you at least appreciate how amazing the process is.
First of all, some basic facts about our Sun:
Our Sun is a G2 V type main sequence dwarf star (medium sized), at the centre of the solar system and contains nearly 99.9% of the solar systems mass. It is a near perfect sphere with a diameter of ~1.3 km.
The colour is white but appears yellowish due to the scattering of blue light in the atmosphere. It is a population I star, rich in heavy elements ( a high metallicity). The Sun was probably formed from a high proportion of material from prior supernova events (death of super massive stars way bigger than our own). Its composition is ~74% Hydrogen, ~24% Helium, ~0.8% Oxygen, ~0.3% Carbon, ~0.2% Iron. Its gravity is about 28 x Earth and is about 150 million km away from Earth, or just over 8 light minutes. Pretty cool so far huh?
Each star is different, but starts life the same way in clouds and dust called Nebulas, stella nurseries for stars. To name a few you may have heard of before, Orion, Eagle, Horse head.....
To make a star, all you need is gravity, Hydrogen and time.
Gravity pulls the Hydrogen gas into a swirling vortex. Gravity brings matter together and when you 'squeeze' things together in smaller spaces, they heat up - with me so far? Basically when you compress something, you drive the temperature up. Over 100's and 1000's of years the cloud gets thicker, a large spinning vortex as big as our solar system and at the centre a large dense spinning ball where the pressure builds until large jets of gas burst out at the sides. Eventually a star ignites, throwing off any remainder gas out. This is at a temperature of 15 million degrees at the core, atoms of gas fuse together. BOOM! A star is born :)
So, we now know how a star is created, what about what drives a stars energy then? Atoms of Hydrogen smash into each other, this process is called fusion. Hydrogen atoms naturally repel one another, chemistry 101, but if they travel fast enough, really fast, they crash into each other, fusing together to make Helium, there go - heat with a small amount of pure energy. The Hydrogen gas weighs slightly more than Helium, it looses mass during the collision and this mass turns into energy.
Stars are huge, and to drive this you need gravity to compress the star to create nuclear fusion at its core.
What happens when the fuel runs out? Well, eventually it will run out, bigger stars use their fuel more quickly so the bigger the star the shorter life. Gravity is in a constant battle with the stars fusion process that they balance each other out, however gravity eventually wins the battle. Our Sun is no exception. Every second it burns 600million tonnes of its Hydrogen fuel. As Hydrogen gets used up, the core slows down giving gravity the edge, with less fusion pushing outward, gravity pushes inward and as fusion fights back the star begins to expand. This is called the red giant stage that consumes all the inner rocky planets, and most likely even the Earth. This is the end of our Earth at this point.
With no Hydrogen left to fuel it, the star starts to burn Helium and fusing it with Carbon. Blasting energy from its core to the surface, these energy waves blow away the stars outer layer, slowly, it disintegrates into a white dwarf. White dwarf is so dense, that is a sugar cube amount was placed on Earth, it would fall right through!! Astronomers believe that in the core of a white dwarf is solid Carbon, literally a diamond in the sky!
This is the outcome of our star, but what about bigger ones? Larger stars have a much more violent ending than our G type star. The gravity of these stars are so massive that they can smash together bigger and bigger atoms. The core of these stars are like factories, manufacturing heavier and heavier elements which leads to the stars destruction. Gold, Silver, Nickel and other elements are all created in these stars. The next time you wear your gold chain or ring, just think, it wasn't created here on Earth, but in the death of a super massive Nova - how bloody cool is that huh!!!
Once the star starts making Iron, this is the end. Iron absorbs the energy in a 1000th of a second, robbing it of its remaining fuel until gravity wins and the star collapses. It creates such a huge explosion, a supernova, the single most violent event in the Universe. Spewing everything out into space. Then, the whole process of star formation begins again. If it wasn't for these massive explosions, our Sun wouldn't be hear, therefore so wouldn't we.
There is only so much Hydrogen in the Universe, Astronomers believe that eventually, the entire universe will simply run out of the star forming gas and eventually, the lights will all go out. Thankfully, we will not be around to see this, nor see the death of our own star in about 4.57 billion years, its already 4.57 billion years old, middle aged. We have a long time to appreciate it and, also complain about it when it feels too hot - but, really, its not the suns fault that I am hot today, it is our atmosphere and environment that causes the temperature - really we should just be thankful that its rises, sets and rises again, because without it - its goodnight sweetheart :)
Carbon, Oxygen, Iron in our blood
Everything around us came from the belly of a star
We are in a 'golden age' of the universe
A good time to be here, seeing the best of all stages of the universe, filling the darkness with light
For we are all made of stardust
Janine Marshall
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