It’s a beautiful, sunshiny day where we live!
My favorite thing about a nice day like this is feeling the warm sun on my face.
But did you know, aside from just feeling nice, the sun’s warmth is a kind of energy?
(Squeaks squeaks)
You’re right, Squeaks!
We use energy from the sun’s light and heat for lots of things!
When you use the energy from the sun, that’s called solar power, because “solar” is
just another word for things that come from the sun.
Have you ever seen a bunch of big, flat, black rectangles on top of a building?
Those are solar panels.
They take sunlight and turn it into electricity!
Some people also collect the heat from sunlight to warm their homes or heat their water.
I even built Squeaks to run on solar power!
(Maybe Squeaks is wearing a pair of sunglasses or something)
You know, Squeaks, this warm, sunny day got me thinking about a cool project we can do
together to use the sun’s energy ourselves.
Want to try it?
[Squeaks agrees]
Okay, let’s do it!
We’re going to build something called a solar updraft tower.
Since it has the word “solar” in it, you already know that it has something to do with
the sun.
“Updraft” just means a kind of wind where air moves up.
And you know what a tower is!
So, can you guess what our solar updraft tower will do?
It’ll take sunlight, and use that to make air move upward through the tower and spin
this paper pinwheel!
You can try this project at home, too.
First, you’ll need three clean tin cans that with the tops and bottoms cut off.
Make sure to get a grownup to open the cans!
You’ll also need some tape,
a paper clip,
a thumbtack,
and two books that are about the same thickness.
They should be pretty big books.
Then, ask a grownup to cut a piece of paper into a square, 15 centimeters — or about
6 inches — on each side.
And, most importantly, you need a sunny day!
Now we’re going to build the tower.
First, stack up the cans and tape them together really well.
Next, bend the paperclip into an arch shape like this, and tape it to the top of the tower
of cans.
Then, get a grownup to help you attach the thumbtack to the top of the paper clip shape
with tape, like this!
Now, we’ll fold the pinwheel.
Grab your square paper and have a grownup help you cut diagonally from the corners.
Don’t cut all the way through the paper, though!
Stop cutting about this far from the middle.
Once all the corners are cut, fold them like this, and tape them together in the center.
Done!
Then get your grownup to stick the pinwheel onto the pointy end of the tack.
Our tower is ready!
All we have to do now is put the can tower on top of the books, so there’s a gap at
the bottom, and set the whole thing near a window, where there’s direct sunlight — so
the sun is shining straight through the window.
And now we wait.
It might take a while, depending on how warm and sunny it is where you are, so be patient
and check on your tower every now and then.
After a while, something really cool will happen!
Whoa!
The pinwheel is spinning!
(Squeaks squeaks)
It isn’t magic, Squeaks!
It’s science!
When the sun shines on the cans, the cans get hot.
Some of that heat travels through the metal to the inside of the cans, so there’s hot
air inside the tower.
And hot air rises.
Squeaks, do you remember when we learned about how hot air balloons work?
Well, this is the same kind of idea.
Air might seem like it’s made of nothing, but it’s actually made of lots of little
tiny particles, way too small to see.
When sunlight heats up the air inside our tower, the heat makes those tiny particles
start to bounce around faster and spread out.
Warmer air that’s more spread out like that will move upward so it’s on top of the cooler
air that’s less spread out.
It’s a lot like how a plastic spoon will float on water!
In our tower, that means that when the sun warms up the air inside the cans, the warmer
air will move upward through the tower and make the paper wheel spin as it passes by.
Then cooler air comes in through the gap on the bottom of the tower, gets heated up, and
rises, so there’s a constant flow of warm air that keeps the wheel spinning.
We’ve made a solar updraft tower.
There are some places in the world where they actually use giant solar updraft towers to
generate electricity!
So the next time you feel the warm sun on your face, remember that it’s more than
just a nice feeling — sunlight is a powerful and useful source of energy.
It’s the same energy Squeaks uses to get around!
(Squeaks squeaks)
Thanks for joining us on SciShow Kids!
And thanks to Google Making Science for helping us with this episode.
Did you make a solar updraft tower of your own?
We’d love to see it!
Grab a grownup to help you send a picture to Kids@SciShow.com, or leave a comment for
us down below!
Bye!