A few days back, we found out how many atoms a person is made up of.

To recap, a typical 70 Kg male would be made up of approximately 7 × 1027 atoms. In general, a person has roughly 1026 atoms for every Kg of his/her weight.

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Now what if all these atoms were laid out end to end? How long would that be? Basically what’s the combined length of all the atoms in your body?

Well, let’s do the maths! In the earlier article, we had also seen the break up of the different types of atoms in the human body. So for a typical 70 Kg male, the break up was:

Hydrogen – 4.22 x 1027
Oxygen – 1.61 x 1027
Carbon – 8.03 x 1026
Nitrogen – 3.9 x 1025
Calcium – 1.6 x 1025

We’re not including the other elements in our calculations since the above elements make up more than 99% of the atoms in the human body.

Of course, different elements have different atomic radii. We take the empirically measured values for the purpose of our calculations :

Element No. of Atoms Atomic radius

(in picometer)

Atomic diameter

(in picometer)

Combined length

(in meter)

Hydrogen 4.22 x 1027 25 50 2.11 x 1017
Oxygen 1.61 x 1027 60 120 1.93 x 1017
Carbon 8.03 x 1026 70 140 1.124 x 1017
Nitrogen 3.9 x 1025 65 130 5 x 1015
Calcium 1.6 x 1025 180 360 5.8 x 1015
TOTAL 5.272 x 1017

*1 picometer = 10−12 m
*values taken for a typical 70 Kg lean male

5.272 x 1017 meters! That’s A LOT!

Time to put it into context. The Earth is 12,742 Km in diameter. That means there’s enough atoms in a human body to go around the Earth over 41,374,980,379 times. That’s over 41 billion in case you’re wondering.

Ok, time to think bigger! According to NASA, the diameter of the solar system is 9.09 billion kilometers. Even that’s puny in comparison. The solar system could be encircled 58000 time.

Time to think in truly astronomical terms now! 5.272 x 1017 meters – How much is that in light years? Light is the fastest thing in the universe, travelling 3 x 108 meters every second! A light year is the distance covered by light in an entire year. Well, the answer is… 55.73 light years! That’s right, if the atoms in the human body were laid end to end, even light would take over 55 years to cover that distance!

Now, the diameter of the observable universe is estimated to be 93 billion light years! Dividing that by 55.73, we get approximately 1.67 billion. The population of Earth is roughly 7.34 billion! So, if we laid all the atoms of all the people on Earth end-to-end, we’d make a line long enough to go across the entire Universe multiple times. Even if we scale our figures to take into account the percentage of children in the world population, and assume that the average weight of all people on Earth would be around 55 Kg, there would still be enough atoms to cover the Universe between 3.5 to 4 times!

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