1Hi, it's Jay.
2When I was a kid, on certain special occasions like New Year's Eve or the Fourth of July,
3my family would gather outside after sunset.
4We weren't the only ones.
5Big crowds of families would gather in the dark,
6everybody looking up and waiting for the same thing.
7Fireworks.
8Each of us had our favorites.
9Some like the colorful ones.
10Others like the ones that made shapes.
11I like the biggest ones best.
12But I also really like the ones that sparkle all the way down.
13Someone named Aaron has a question about fireworks.
14Let's call Aaron now.
15Hi Jay.
16Hi Aaron.
17I have a question for you.
18How do fireworks work?
19That's a great question.
20There are so many different kinds of fireworks out there.
21There's everything from small handheld sparklers to enormous, complicated fireworks displays timed to music.
22Maybe you've seen fireworks before and love them.
23They're colorful and dazzling and like nothing else.
24Or maybe you find fireworks scary.
25They make really loud noises and maybe they seem dangerous.
26I mean, isn't that fire up there in the sky?
27I'm curious, have any of you seen fireworks before?
28What was that experience like?
29Fireworks are beautiful and incredible, and they can be dangerous, too.
30Those dazzling lights come from explosions.
31Explosions are big bursts of light and heat and sound.
32The bigger the firework, the more careful planning it takes to make sure the explosion stays safe.
33Different places have different laws about who and where and how fireworks can be handled.
34And even when they're handled safely,
35anything that makes a loud bang and bright flash has an impact on the living things around it.
36Some really don't like them.
37Nevertheless, fireworks have been popular for a long time.
38Fireworks first burst onto the scene thousands of years ago in China.
39Inventors in China discovered how to make a highly explosive powder.
40When they poured that explosive powder into hollow tubes of bamboo and set the tubes on fire,
41it created a loud, brilliant boom.
42Those tubes were some of the first fireworks.
43Since then, inventors around the world have found ways to make more and more complex and decorative booms.
44The fireworks we see at big events like holidays and sports games these days have come a long way from thin tubes of bamboo.
45Each of these tubes is one firework.
46Look how big they are.
47Today we're going to focus on these big fireworks, the ones handled by professionals.
48For a firework like this to work, two things have to happen.
49First, you need to launch the firework into the air.
50You do not want a huge firework like this going off on the ground.
51Second, once that firework is high in the sky,
52then you need to make it explode in a thrilling blast of color and light.
53Let's start with that first part.
54To launch a firework into the air, a cord called a fuse is lit on fire.
55The fire travels up that fuse.
56When the fire reaches the bottom of the firework, it sets something else on fire.
57A whole bunch of explosive powder.
58When that powder catches fire, it explodes in a huge burst of light and heat.
59But that light and heat is not the final explosion you see in the sky.
60Not yet.
61Instead, this first explosion of powder launches the rest of the firework up into the air like a rocket.
62Now, it's time for step two.
63Explode the firework in midair.
64But how do we make that explosion happen?
65We can't have a person light it with a match like we could on the ground.
66But here's the thing, we don't have to.
67That first explosion on the ground did more than launch the firework into the air.
68It also set fire to a second fuse.
69As the firework flies up and up, that second fuse is burning and burning and burning.
70Eventually, the fire on the fuse reaches the main part of the firework
71and the whole thing goes like this,
72or like this,
73or like this.
74What a firework looks and sounds like when it explodes depends on what's inside.
75Usually, this is some combination of powdered metals and other chemical parts.
76Different materials explode differently.
77For instance, this is what a firework that contains copper looks like when it explodes.
78It's blue.
79A firework containing titanium looks like this: white.
80A firework with a material called strontium makes this: red.
81In some cases, firework designers even mix colors together like you do with paints.
82So strontium which makes red mixed with copper which makes blue equals purple.
83And it's not just colors.
84For example, the material charcoal burns for a long time.
85So fireworks that have charcoal in them stay brighter for longer,
86making an explosion that looks kind of like falling streamers.
87Certain chemicals make louder booms than others.
88Others explode in a crackling or popping sound.
89How chemicals are packed and arranged inside the firework makes a difference too in the shape of the explosion.
90Whether it's a circle, a star, or even a smiley face.
91So, in summary, fireworks are a series of explosions.
92One explosion launches the firework into the air
93and another explosion makes the firework explode in dazzling lights.
94Fireworks have been thrilling onlookers for thousands of years.
95But over time, inventors have found ways to make more and more colorful and complex explosions.
96Different arrangements of different chemicals make different colors, sounds, and patterns.
97What should we invent next?
98A rainbow firework, a quieter firework?
99Or how about this?
100These drones fly together to create stunning changing light displays in the sky
101without all the danger and fuss of exploding fireworks.
102How else could we create incredible things to look at to help us celebrate our big moments?
103That's all for this week's question.
104Thanks for asking, Aaron.