We are stardust!

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Did You Know That with Alan Walter

“We are stardust……billion-year old carbon,” Joni Mitchell - Woodstock

Everything we see around us in the world today is made up of atoms and molecules that for the most part did not exist at the beginning of our universe. Atoms such as carbon and oxygen that make up our bodies were simply not around at that time. So where did these and other heavier atoms like iron, silver and gold come from?

At the very beginning, some 13.7 billion years ago, the only elements existing were countless lighter atoms of helium and hydrogen floating around in space. Over time, gravitational attraction began working between them and they moved to cluster together in large quantities to create the first stars. The gravitational force acting to squeeze these atoms together became so strong that nuclear fusion was ignited. For the first time in the cosmos, light produced by this fusion was seen in space. Imagine total darkness in the universe being replaced by the first beacons of light as these stars progressively turned themselves on.

The size of these first stars determined how long they were to live. Smaller stars lived much longer than the giant stars, and when their nuclear fuel had run out after a few billion years they faded away to barely visible, very dense objects. This will be the fate our own Sun, a moderate sized star, which is calculated to last a further five billion years.

Very large giant stars live a very short life, just a few million years, because they eat through their nuclear fuel very rapidly. Their end however is spectacular as they collapse in on themselves and go “supernova”. They massively explode and the light they produce can be brighter than a billion stars in the sky and it can last for up to a day of our time.

As an aside, astronomers are able to detect many such supernova happenings every year in our own and distant galaxies, and in fact the intensity of the light from them is used as a measure of how far away these galaxies are.

The important thing about these supernovae events is that in this catastrophic process temperatures reach millions of degrees, and atoms of helium and hydrogen are under huge pressure. New heavier atoms are created, including the elements that are essential to our existence such as oxygen, carbon and iron; and the more exotic and even heavier elements such as silver, gold and uranium. 

As the star finally explodes all these elements are literally blown into space; this is truly stardust that awaits an amazing future. That future is the creation of new stars, through the same gravitational forces. This time however, because of the variety of atomic materials available, planets like our Earth can be formed circling the new star.  They contain their share of the heavier atoms like oxygen and carbon which can be the makings of life on the planet under the right conditions.

All this is brought home to me when I see a piece of gold such as a wedding ring on someone’s finger. My instinctive reaction is to say to myself……

“I know where you came from. You were born in a supernova maybe billions of years ago and some billions of miles away. We are both stardust. I just happen to be made of plain old billion-year old carbon.”     


Alan Walter is a retired professional engineer living in Oxford. He was born in Wales and worked in Halifax. He spends much of his time in Oxford, where he operates a small farm. His column will appear bi-weekly.





Geographic location: Oxford, Wales, Halifax

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