If you have ever been to an aerial fireworks show, then you know that fireworks have a special and beautiful magic all their own -- a good show is absolutely amazing. Have you ever wondered how this magic works? What, exactly, gets launched into the sky to make these beautiful displays?

Firecrackers and Sparklers
In order to understand how aerial fireworks work, it's good to take a close look at sparklers and firecrackers. The sparkler demonstrates how to get bright, sparkling light from a firework, and the firecracker shows how to create an explosion.

Firecrackers consist of either black powder (gunpowder) or flash powder in a tight paper tube with a fuse to light the powder. Black powder contains charcoal, sulfur and potassium nitrate. A composition used in a firecracker might have aluminum instead of or in addition to charcoal in order to brighten the explosion.

Sparklers are very different from firecrackers. A sparkler burns over a long period of time (up to a minute) and produces extremely bright and showery light. A sparkler consists of several different compounds, including a fuel, an oxidizer and a binder.

Image © AakaashBali/iStockphoto.com

The fuel is charcoal and sulfur, as in black powder. The oxidizer, which is basically a chemical oxygen storage container, might be something like potassium nitrate. Many chemicals are rich in oxygen and, when heated, will release that oxygen as a nearly pure gas. The oxygen is important because that's what helps the sparkler continue to burn. The binder can be sugar or starch. Mixed with water, these chemicals form a slurry that can be coated on a wire (by dipping) or poured into a tube. Once it dries, you have a sparkler. When you light it, the sparkler burns from one end to the other. The fuel and oxidizer are proportioned, along with the other chemicals, so that the sparkler burns slowly rather than exploding like a firecracker.

Aerial Fireworks
An aerial firework is normally formed as a shell that consists of four parts. The container is usually pasted paper and string formed into a cylinder. Inside the container are stars -- spheres, cubes or cylinders of a sparkler-like composition. A bursting charge is located in the center of the shell and a fuse provides a time delay so the shell explodes at the right altitude. Located just below the shell is a small cylinder that contains the lifting charge.

The shell is launched from a mortar. The mortar might be a short, steel pipe with a lifting charge of black powder that explodes in the pipe to launch the shell. When the lifting charge fires to launch the shell, it lights the shell's fuse. The shell's fuse burns while the shell rises to its correct altitude, and then ignites the bursting charge so it explodes.

Simple shells consist of a paper tube filled with stars and black powder. Stars come in all shapes and sizes, but you can imagine a simple star as something like sparkler compound formed into a ball the size of a pea or a dime. The stars are poured into the tube and then surrounded by black powder. When the fuse burns into the shell, it ignites the bursting charge, causing the shell to explode. The explosion ignites the outside of the stars, which begin to burn with bright showers of sparks. Since the explosion throws the stars in all directions, you get the huge sphere of sparkling light that is so familiar at fireworks displays.