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When we think of the word ‘universe’, we should probably think of hydrogen.

Hydrogen is a colourless, odourless, tasteless, but highly flammable gas. It’s the element that makes up 74% of all ordinary matter, lights the stars and in doing so illuminates the universe.

In the seconds following the Big Bang almost all of the universe’s hydrogen was created as quarks coalesced into atoms. Hydrogen is the simplest element to make with just one proton and one electron, and because of that simplicityΒ a lotΒ of it was made.

Through the interplay of the huge hydrogen clouds that followed the Big Bang and the influence of their own gravity, the large structures throughout the universe like galaxies, dust clouds, and stars were formed.

When a cloud of hydrogen coalesces into a star, it becomes the main fuel that the star uses through nuclear fusion. In our own Sun, 600 tons of hydrogen are fused in every second. Through hydrogen, stars like the Sun heat and illuminate the universe.

The light and heat of stars come from fusing elements like hydrogen and helium in their cores.

When a star reaches the end of its life, many of them explode in a supernova. The resulting shockwave creates a multicoloured gas cloud called a nebula, and many of them are stunning.

Some of the most beautiful shapes in space are nebulas. This is the Omega Nebula, which is about 90% hydrogen, unused by a long dead star.

When the next generation of stars and planets are being formed out of nebula clouds, most of their material is hydrogen, either left over from the Big Bang or unused by a long dead star. This is why the gas giants Jupiter, Saturn, Neptune, and Uranus are about 90% hydrogen.

Down on Earth, we are not able to recreate the conditions of immense pressure of stars that fuses hydrogen, but because it’s light and flammable, we’ve worked out a few uses for it like fuel and a lighter-than-air gas.


When hydrogen burns, it gives off very few pollutants and zero carbon dioxide. Some energy companies are promoting it as an emissions-free alternative to gasoline.

It is sometimes used as rocket fuel, but it takes up a lot of volume for its weight. So we cool it into a liquid to fit more in a container. But this usually creates its own problems. The containers have to have thick heat-resistant walls that must be constantly maintained, which makes it more expensive.

The Delta IV rocket used liquid hydrogen mixed with liquid oxygen as a propellant.


Hydrogen was once used as the gas that gave lift to airships and zeppelins. Nowadays we use helium, though it’s rarer, more expensive, and weighs more than hydrogen, but it also doesn’t explode.

Hydrogen hasn’t been popular since an airship called the Hindenburg exploded in 1937.

But in 1937, helium was the subject of a production monopoly by the United States, who refused to export it to any other country (including the Germany-based zeppelin company) under the probably not unfounded concerns that it might be used for military purposes.

So although the zeppelin engineers at the time were aware of the explosiveness of hydrogen, they decided to use it the only fuel that was available.


The concentration of hydrogen ions in a solution is what makes something acidic.

But the most interesting thing about this element is that everything around you, from the skin and bones of your hands to the metals in your phone, was once hydrogen. How this came to be you is a bit of a longer story.

The Hindenburg explosion.

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Ben McCarthy

Ben McCarthy

Ben is the Founder of Discover Earth and the author of the Big Ideas Network.