We are star stuff

Carl Sagan famously said this many times: “We are star stuff”. But what does that actually mean? Was he being metaphorical? No actually, we are quite certain that the early universe consisted of mostly hydrogen and a little bit of helium. As pockets of these gases started coagulating into larger formations, they became denser. Once they got large enough these gas balls became so hot in their core that fusion began. Voila, I just described the birth of a star. Fusion has one way or another created most elements of the periodic table. Including the very stuff that we are made of.

What is Fusion?

Fusion is simply 2 hydrogen atoms combining to create one Deuterium atom. Add another hydrogen atom and you get Helium. You lose protons in the process. These extra protons result in an energy release. This is how stars are created. A typical star will keep smashing atoms together creating different elements. For instance, once 2 helium atoms are fused into one, they will make Helium-3. Two Helium-3 atoms will produce Helium-4 and two Helium-4 atoms smashed together will make Beryllium. This process continues all the way up the periodic table to iron. There is more to the process but those are the basics. A better example is in the image below.

Hydrogen to Helium

Once stars start producing iron there are no extra protons left over in the process to make energy. This is typically a death blow for the star. Since there is no outward pressure from the energy release the star will slowly collapse in on itself and if the star is large enough it will go supernova. Really massive stars can even turn into neutron stars and when 2 neutron stars collide even heavier elements can be formed in the process. Neutron stars are so large they border on collapsing into black holes. Massive stars have short lifespans, so new elements are constantly being created.

Nebulae are star factories

If you’ve seen a picture of a nebula, this is the cloud that forms stars and their planets. All the elements needed to create a star and its neighboring planets, moons and asteroids are present in the gas field. All that is needed to get the process started is a gentle push. The gas will be pushed together by a supernova close to the cloud, and gravity will then take over.

carina nebubla

You are star stuff

The human body is composed of mostly 6 elements. Oxygen, hydrogen, nitrogen, carbon, calcium, and phosphorus. These six elements can be found in a typical star like our own. The elements that make up your body right now did not exist at the beginning of time. They were made from fusion within a star at some point in time. Therefore, every atom that exists in your body today was created inside of a sun. You are star stuff.

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