Did you know that your body – bones, blood, breath – is made of ancient stardust? Scientists say we are all made of the dust of stars because your body contains 7 octillion atoms. To visualize, 7 octillion equals 7 with 27 zeros. Even when converted to billions, it is still 700,000,000,000,000,000,000 billion. The particles from across the cosmos have come together to create you.
Your body is a vast collection of atoms. The body of an average person (weighing 70 kg) contains approximately 7 octillion atoms. These atoms constantly change as you breathe and eat – always incorporating new ones. These atoms are billions of years old, formed not on Earth but in the universe.
Source: aajtak
Your body consists of 21 chemical elements, but 99% of it comes from just 6 elements.
Let's see by weight...
Oxygen (O): 65% – in water and air, the most in bones and muscles.
Carbon (C): 18% – the basis of cells, found in DNA.
Hydrogen (H): 10% – part of water (H₂O).
Nitrogen (N): 3% – in proteins and muscles.
Calcium (Ca): 1.5% – in bones and teeth.
Phosphorus (P): 1% – in bones and energy (ATP).
Source: aajtak
Now, by the count of atoms...
Hydrogen: 63% – the most numerous but light.
Oxygen: 24%.
Carbon: 12%.
The remaining 1% includes elements like iron (Fe) in blood, and potassium (K) in nerves. In total, 96% of the body is made up of just 4 elements (O, H, C, N).
These elements were not formed on Earth. The universe began with the Big Bang 13.8 billion years ago.
Back then, only light elements were created:
Hydrogen (H), helium (He), and a bit of lithium (Li). Hydrogen makes up 60% of your body by number – almost as old as the universe. Other heavy elements were formed in stars. Scientists call this stellar nucleosynthesis.
Stars create heavy elements by fusing hydrogen, such as carbon, nitrogen, and oxygen in small stars. Calcium and phosphorus are made in bigger stars.
Source: aajtak
When a star dies, a supernova explosion scatters these elements into space. 93% of your body's elements come from stars. A study of 150,000 stars shows that we truly are stardust. Iron? Formed in stellar cores, spread by supernovae, and is billions of years old in your blood.
Old stars were made of hydrogen and helium. Newer stars have more metals. These elements formed clouds, created the solar system, then Earth, leading to plants, animals, and humans. Each breath of oxygen you take is thanks to stars. 99% of the elements come from stars or supernovae. You are a part of the universe—neither small nor separate.
