Helium

We have had a few birthdays around the lair this week. Zaltu turned three, along with a few other mini-minions around the neighbourhood. And with birthdays come the parties, and with parties come balloons.


At one party, Zaltu became enamoured with a big bright blue balloon. It had a shiny skin and a sparkly silver tail trailing down to her tiny little wrist. It was almost as big as her eyes.

And then she stepped outside.

And whichever numpty tied the balloon to her wrist was clearly not a knot-expert.

<it was me>

There is nothing as forlorn as a small child watching their big bright blue balloon float up into the big bright blue sky.

Well, except for seeing said child staring helplessly at the balloon stuck in a tree just out of reach. 

To Zaltu’s credit, she didn’t freak out or throw a tantrum, or collapse into a meltdown. She was upset, and there were some quiet tears, but instead she turned to me and asked: “why does my balloon fly away?”

So I SCIENCED!!

<insert dodgy 80’s music>


And we talked about Helium (remembering she is 3yo):

We talked about how the air we breathe is made of lots of different gases; some gases we want to breathe in like Oxygen because it is how we live. Some gases we breathe out, like Nitrogen because we don’t need it in our body in such a large dose. Another gas is Helium, which we can neither see, taste, nor smell. 

Helium is really light compared to other gases. For example, the nitrogen we breathe out is about 8 times heavier than helium. When we blow nitrogen into a balloon, the balloon weighs it down so it only has a light buoyancy – enough to sort of bounce, a bit.

Helium, however, is light enough to lift a lot of things, at a rate of about 1 gram to every litre of helium you are using.

This also means you can weigh down a helium-filled balloon, without impacting on its buoyant appearance. This could be a rock, or a tree, or a person. 

Over time, the helium will leak out the balloon – it is a gas do it can leak out even the smallest gap. The more that leaks out, the less helium available to float the balloon.

While we were having this discussion, the lovely hosts of the birthday party brought Zaltu another balloon. They also taught me how to tie a better knot. Because evidently, I suck at it.

However, Zaltu stopped them from tying it to her wrist.

Instead, she looked at the balloon. Then looked at her body, then looked at me.

Back to herself. Back to me… 

“Mum. You better hold my balloon. Your bigger weight is better to hold my balloon down.”

Yeah. Thanks for that. 

Fine. I’ll have another piece of cake, thanks – for Zaltu’s sake, of course. 

Sidenote: there’s a bit of debate on whether helium balloons are environmentally friendly. The Surfing Scientist said it best with his fairly detailed answer. And yes. We did go back to collect the ribbon once the first balloon came down from tree.