High school

Are we all made of stardust?

Today I would like to drift a bit aside from Biology and move on to my last year of high school, when after two years of Chemistry and Biology we started studying Astronomy. We moved from studying atoms and molecules in the infinitely small to study atoms and molecules in the infinitely big and in phenomena that in our life time we would never (realistically) have the chance to experience.

Something that I always hated during my years in high school in Italy was the fact that as students you do not have the chance to choose the subjects you want study during high school (compared to other places in the world as it could be the case in the USA). Basically in Italy when you are 13 years old you have the chance to choose the type of high school you want to attend (for example, an high school with a more scientific direction, rather than one with a more literary approach, or a more technical high school that is supposed to prepare you directly for a job) and then you are forced to study subjects that are not even close to your likes. However, looking back at it now, after almost 10 years from my last day of school, I actually had the chance to try to study many different things, that then allowed me to first expand my (still) limited point of view on many subjects, and then gave me the chance to decide what I liked best for my future studies.

Astronomical geography was one of these apparently pointless topics. In the beginning I thought: “What the heck?! Why do I have to study the universe and its astronomical coordinates? What is the point of knowing how stars are formed and how things are revolving in space? Who cares about the theories on how the universe started and how everything will end? I was not there for it and for sure I will not be here when everything will go to hell or whatever”. As always, I then realised how the study of our universe was actually fascinating and mesmerising, because we are nothing more than stardust as we “..couldn’t be here if stars hadn’t exploded, because the elements – the carbon, nitrogen, oxygen, iron, all the things that matter for evolution – weren’t created at the beginning of time.” Lawrence M. Krauss, A Universe from Nothing: Why There Is Something Rather Than Nothing 

This is exactly the point were I started having doubts about choosing to study a Biology related subject during my university studies. Figuring out how the universe formed, “discovering” new planets, finding a cometh in the sky or just even better understanding my own planet was so intriguing that I actually started considering to abandon Biology and put my mind and energies in this topic. The only thing that prevented me from choosing this instead of Biology was the huge amount of physics I would have had to study (I always had a love-hate relationship with physics that sooner or later I will talk about), but also the fact that the study of the universe is right now (as I could imagine) a work you do in front of your pc analysing data you get from huge telescopes or other devices. But more of this later on.

Since I mentioned the stardust let’s see in the SFR what it actually is and why we can claim we are all made of stars.

“Science Related Fact” (SRF):

Stars are basically power plants able to convert light elements (like hydrogen) into heavier ones (such as helium, beryllium and so on) via nuclear fusion. Indeed, when the universe was born the only existing element was hydrogen and the first young stars started converting hydrogen to produce helium and generate a huge amount of energy. However, once they run out of hydrogen, they began to transform helium into beryllium and carbon and they started burning these heavier nuclei and synthesizing heavier and heavier elements.

As I mentioned above, before the birth of our solar system, there was a very large star that spent its life converting hydrogen into helium, but as the hydrogen got depleted and converted to helium, the star contracted and started to compress helium, allowing to its conversion into heavier elements. With each cycle the star became hotter, smaller and denser, as it is more difficult to convert heavier elements, therefore each cycle of elements’ conversion became shorter. What large stars basically do is live fast, die young and go out with impressive “fireworks”.

“Remains of a massive star that exploded, spewing its gaseous layers out into an already turbulent region”. From NASA/ESA/HEIC and The Hubble Heritage Team, nasa.gov.

These “fireworks” are called supernova and when a star becomes a supernova the process is so violent that much heavier elements are created by the unimaginable forces of the star’s death, force that in the meanwhile is also scattering the stardust around. These ashes of the dead star are in gasses and dust floating around that eventually, with a little gravity, will start to form clumps. The central portion of one of these clumps will eventually form a new star, grabbing up a large part of the leftover hydrogen (as it happened to our sun), while the heavier stuff further out is swept up by the planets.

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