Hello everyone! I hope you enjoyed learning about George Washington last week (I sure did) but now it’s time to move on.

This week’s Theme of the Week is Hot Air Balloons #bobbledyhotair !!! I LOVE hot air balloons! They are so cool! Or should I say HOT?!

photo by DarlArthurS

If you haven’t seen hot air balloons in real life before, then you probably don’t realize just how gigantic they are.

Holy cow!! That is enormous!!!

Hot air balloons are able to float because hot air is lighter than cold air. I know – that’s weird, because how much does air really weigh anyway? Have you ever lifted air?

(OMG I just tried to find out how much air weighs. If you’re interested in how a simple question can have a very complicated answer, check it out here!)

Well, the fact is that even though air doesn’t seem heavy to US, it does still weigh something. And hot air is lighter than cold air. SO – if you heat air, it goes up. We don’t really notice this, because we can’t see it happening. BUT – you might have noticed that when you roast marshmallows over a fire, the air ABOVE the fire gets hotter than the air to the sides of the fire. That’s because the hot air is floating UP (not sideways, or down).

So what a hot air balloon does is actually catch the hot air and keep it inside. Then, the hot air will make the balloon itself float up, because the hot air inside is lighter than the cooler air outside the balloon. Apparently, if you know anything about flying hot air balloons, the best days to fly are ones that are cool and clear, because it’s much easier to get the air inside the balloon hotter than the air outside if the air outside is cool. Got it?

Hot air balloons have big burners inside, just above the basket. They heat up the air to inflate the balloon, and then keep the air hot while the balloon is up in the air. The “pilot” of a hot air balloon turns the heater on if he wants the air to get hotter (and float higher) and turns it off if he wants the air to cool off (and sink lower).

Here’s a cool video showing how the burners work. You can see how hard it is to inflate a hot air balloon!

Now, most of us are familiar with these great big hot air balloons, but hot air balloons weren’t always the big giant ones. The very first ones were quite small. They were invented in China over 1,700 years ago by a warrior named Zhuge Liang. He made his out of a very light paper bag with an oil lamp attached to it, and when he sent it up in the air at night, it glowed. He was able to signal to other troops fighting with him – and it also confused his enemies, because they couldn’t figure out what it was.

If you’ve seen Tangled, it’s just like the sky lanterns that Rapunzel wanted to see:

(and if you HAVEN’T seen Tangled, you MUST! Go do it RIGHT NOW!!!)

There are actually festivals in China and Taiwan and Thailand where thousands of people come together and send their sky lanterns floating up into the sky, just like in Tangled. And it’s even more beautiful in real life.

Of course, sky lanterns are kind of dangerous because what comes up, must come down. Usually the fire has gone out by the time the sky lantern comes back to the ground, but there’s also the problem that most people don’t go looking for their lantern after it falls to put it in the trash. (If you want to learn more about how much trash we’re generating these days, you can look at our Garbage Theme of the Week!).

It wasn’t until about 200 years ago that people started making the giant balloons for people to ride in. Before they figured out what the best way to make hot air balloons, they had lots of different ideas of what might work:

And, because they weren’t sure if it was safe for people to travel by hot air balloon, the very first passengers on a hot air balloon were a sheep, a rooster and a duck. Yep! As part of this first flying experiment, the balloon designers wanted to test the effects of flying on animals that were already able to fly as well as an animal that would never be able to fly. They picked a sheep because apparently back then, they thought sheep were the most similar to humans. (In case you’re worried, the animals all survived the experiment without any problem.)

So that’s it! That’s all you need to know about hot air balloons!! If you learn anything more interesting, please add it in the comments below. And also answer this question: if you could take a hot air balloon ride, where would you go and who would you take with you?

Stay tuned on Monday for Matthew’s story about hot air balloons!!

okay, andd if you aren’t totally tired of hot air balloons by now, check out this craziness:

Happy Hot Air Balloon Week!!