Imagine if our world had a diary and on the interesting days, someone pulled out a big book and wrote about it.
Day 21 was such a day and as important as days go, this was a big one for us. Not much to The Universe, but definitely a big one for humans. There is little that could be more important to us than the birth of our star.
One could be forgiven for asking why we are already up to ‘Day’ 21 before we write about the birth of the sun. Why is it not number one or two?
The fact is, an awful lot happened before this significant (to us) but unremarkable (to the Universe) event came about. In fact, two thirds of all the time that ever existed, has passed already and our sun is just being born.
That is such a remarkable statement, I’d like to revisit it.
As ancient as our 4,630,000,000 year old sun is, on the day it was born, two thirds of all the time that has ever existed in our Universe, had already passed by.
This area in the Milky Way had been the site of a fair bit of gas in the form of atoms of hydrogen and helium. It’s way out on a side branch of one of the arms and there are plenty of stars here already, but space is big. Not big as we know it, big like ‘beyond imagination’ big.
Right about where the centre of the sun now resides, about 30,000 lights years from the centre, two atoms of hydrogen were attracted to each other by that weakest of all forces, gravity. Soon, they were joined by a few helium atoms and then a few more and after that a few more and, well you get the idea.
Just up the road a bit, another couple of hydrogen atoms had set up in opposition and were busy collecting friends too.
After a little while, about a thousand million years or so, the sun group was clearly winning the race and had collected so many atoms, there was some serious gravity going on. The pressure, which increases temperature, forced some of the inner atoms of hydrogen to convert to helium, as though there weren’t enough already.
The conversion process is what we like to call nuclear and the steady blasting out of energy was only balanced by the enormous gravity of all the atoms piled on top. We had a slow burner, a star. There’s enough hydrogen there to convert into helium, it should last another 4,600,000,000 years and then some. It’s not quite middle aged for this size and type of star.
In terms of size, the sun, aka Yellow Dwarf star, although the light it generates is white. is average, but far from average in terms numbers. Red Dwarf stars outnumber our star 20 to one. They start out smaller, some where between a tenth and half, but they burn for longer. Much longer. In fact, we are not aware of any burnt out red dwarfs as they happily burn away at much cooler temperatures and can live for trillions of years. The smallest ones that formed just after the big bang are not even middle aged yet.
As most of the stars in our galaxy are red dwarfs, the sun is in the top 15% in terms of brightness. If it had been a red dwarf and therefore less intense, maybe life may have evolved on Venus as it is so much closer to the sun, the earth may be been a bit too chilly.
In performance, our star is pretty normal, if such a thing exists in that it converts about 6 million tonnes of matter, by that we mean hydrogen, into energy but getting off the sun is not easy and said energy takes up to 170,000 years to get away. It’s then express to earth, in about 6 minutes flat.
What of the sun’s competitor? Most commonly, the opposition also bursts into song about the same time creating a twin star system, but a little less commonly, only one makes it.
In our case, later, much later as it happens, humans evolved on one of the scraps of material left over and named the unsuccessful gas bubble ‘Jupiter’. It never did get enough to be a star, not even the smallest red dwarf star and I guess plenty of humans have felt that anguish, of not being a star, albeit of a different variety.
Speaking of scraps, the sun collected everything it could reach but one tiny bit of material we call earth escaped the direct pull and like the rocky planets and the gas planets, orbits the sun under the influence of gravity, making a full circuit once a year. We’re only one millionth of the size so the sun doesn’t actually miss our contribution. Fortunately.
(You can see ALL the interesting ‘days’ in the magnificent science poster which you can download and print. See what it looks like here.)