One of the best things about Independence Day and certain other holidays and celebrations is the fireworks show. It lights up the night sky with brilliant, colorful explosions. The sights and sounds of a spectacular fireworks show can amaze your senses, lift your spirits and inspire your heart.
Although fireworks may seem like pure magic, they’re actually pure science. All those different shapes and colors come about as a result of careful planning when making fireworks.
Experts believe fireworks were invented in China well over 1,000 years ago. Today, China is still the largest manufacturer of fireworks in the world.
Most kids are familiar with two basic types of fireworks: firecrackers and sparklers. Believe it or not, the science behind these two basic fireworks form the basis for those spectacular fireworks displays you see in the sky (called aerial fireworks).
Firecrackers are simple rolled paper tubes filled with black powder (also called gunpowder) or flash paper and a fuse. When you light the fuse of a firecracker, the fire burns along the fuse until it reaches the powder. When it does, you get an explosion.
Sparklers are different in that they make bright, sparkly light for a long time (up to a minute or more) rather than a short explosion. Sparklers contain more substances than firecrackers, so that they’ll burn longer and produce light and sparks. The bright sparks you see are usually burning bits of dust made of metals, such as aluminum, iron, steel, zinc or magnesium.
Aerial fireworks are usually manufactured as a shell that is made up of four parts. The container consists of pasted paper. The fuse allows the shell to reach the desired altitude before exploding. A bursting charge made of black powder (like a firecracker) is at the center of the shell. Stars (sparkler-like substances shaped into small spheres) are mixed throughout the interior of the shell.
These shells are usually launched into the sky from short pipes filled with a lifting charge of black powder. The lifting charge also lights the shell’s fuse, which burns as the shell rises into the sky. When the flame along the fuse hits the bursting charge inside the shell, the shell explodes and the magic begins!
The explosion ignites the stars. The stars burn to produce the bright sparks of light we see in the sky. The explosion pushes the stars in all directions, which creates the beautiful displays we’re all familiar with.
If you’ve ever seen fireworks that seem to explode in different stages, those fireworks use special “multibreak” shells. You can think of them as shells within shells that are made to explode in different phases.
Not all fireworks look the same. Some explode in a circle, while others look like a shower of sparks falling down toward the Earth. The specific pattern that fireworks make in the sky depends upon the way the stars are arranged in the shell. To create a special pattern, manufacturers create an outline of the pattern they want with stars and then surround those stars with a special charge that will separate them all at the same time from the shell.
It takes just as much science to create the beautiful colors we enjoy watching during fireworks shows. Most colors are produced by carefully mixing the right kinds of chemical compounds that will make particular colors when they burn.
Here are just a few examples of some of the chemical compounds used to make certain colors:
- red: strontium and lithium salts or carbonates
- yellow: sodium compounds
- green: barium compounds
- blue: copper compounds