Madeleine Finlay

But not down here on Earth.

Now, down here on Earth, it's made when radioactive elements like thorium and uranium decay.

Where do we find these elements?

In the Earth's crust.

And we're very lucky because the underground formations that trap natural gas are also very good at trapping helium.

So when we mine natural gas, we also pull out the helium.

So that's where helium supplies come from, natural gas reserves.

And I actually got in touch with Sophia Hayes, Professor of Chemistry at Washington University in St.

Louis, who uses helium a lot in her own research.

It centres around nuclear magnetic resonance, NMR, including at very low temperatures.

And she's done work on quantum phenomena in semiconductors.

So she knows helium.

And one thing I wondered was how rare this element actually is on Earth.

Now, the main countries that currently supply helium are the US, which provides right now around 40% of the global supply.

That's been dropping over the years as they've sold off their National Helium Reserve, which once housed over 1 billion cubic metres of the stuff.

After that, there's Qatar, which were supplying around a third.

And then the rest largely comes from Algeria, Russia and Poland.

But a few of the great things about helium, its lightness, its unreactivity, also make it an extremely challenging element to keep hold of because it just tends to float away into outer space, lost to us forever.

Well, because gas is such a pain to transport because it takes up so much room, helium is compressed and it's liquefied.

So once the helium has been mined and it's liquefied, it's put in special containers to keep it cold.