How are we made from star stuff?


Carl Sagan repeatedly said this: “We are star stuff.” But what does that mean? Was he being metaphorical? No, we are pretty confident that the early universe consisted mainly of hydrogen and a little bit of helium. As pockets of these gases started coagulating into more giant 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, in one way or another, created most periodic table elements, including the same stuff that we are made of.

What is Fusion?


Fusion is simply two 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 two helium atoms are fused into one, they make Helium-3. Two Helium-3 atoms will produce Helium-4, and two Helium-4 atoms smashed together will make Beryllium. This process continues 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

Creation of heavy elements

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 it is large enough, it will go supernova. Massive giants can even turn into neutron stars; when two neutron stars collide, even heavier elements can be formed. Neutron stars are so large they border on, collapsing into black holes. Massive stars have short lifespans, so new elements are constantly being created.

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Nebulae are star stuff 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 necessary to get the process started is a gentle push. The gas can be pushed together by a supernova close to the cloud, and gravity will then take over. If the cloud is in a galaxy already, the surrounding stars will give it the push it needs.

carina nebula star stuff

You are star stuff

The human body is composed of mainly six 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 in your body today was created inside a sun. You are star stuff.

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