Fireworks: The Science Behind Ba-Boom ... Ahhh

Creating the perfect fireworks show requires trial and error and planning. Tony Cresciben [CC by 2.0]/Flickr

Nobody doesn't like fireworks.

You can debate the environmental effects of all that flashing and booming until the last sparkler has sparkled and the smoke finally has cleared. But the show itself — the colors, the sounds, the excitement? Who hasn't spent a warm summer evening gazing into the sky, mouth agape, entranced by a shower of falling, twinkling lights?

"It gets back to that childhood glee," says Joe, a pyrotechnic chemistry researcher who asks to go by his nom de boom, "Dr. Pyro." Joe — sorry, that's Dr. Pyro — has belonged to the Maryland-based CrackerJacks club, which claims to be the oldest regional fireworks club in the U.S., for more than 20 years. "Just the fact that you're there and you have these bright lights ... when your senses are excited by bright colors and loud noises ... it's like being on a roller coaster. You go on a roller coaster to be scared. But you know you're safe."

The wonderment of fireworks never ceases. But, just because you're wondering, we'll tell you this: The secret is in the science. With a dab of artistry mixed in.

The science behind fireworks

First, the colors. As MNN science editor Russell McLendon points out, the colors in fireworks are created by burning different metals and metal compounds. He has a rundown of what metals produce each color.

"Although all of the colors and effects of a fireworks display are spectacular," says the American Pyrotechnics Association, "the hallmark of a truly fine show are deep blue or dazzling white bursts — the marks of an expert pyrotechnician."

The metals — packed in "stars," or pellets of various sizes in the shell of the fireworks, and surrounded by explosives — come alive through the wonders of chemistry. "The sights and sounds of each explosion are the result of several chemical reactions — oxidations and reductions," explains University of Wisconsin-Madison chemistry professor Bassam Z. Shakhashiri on his "Science is Fun" website. "Oxidizers produce the oxygen gas required to burn the mixture of reducing agents and to excite the atoms of the light-emitting compounds ... The reducing agents, sulfur and carbon, combine with the oxygen from the oxidizers to produce the energy of the explosion."

Let's back up: The basic act of shooting off the fireworks — getting those color pellets airborne so they can be ignited and do their chemical thing — is a good bit of perfectly timed science in itself.

Fireworks wired to launch in North Charleston, South Carolina. North Charleston/flickr

It starts with a fuse that lights the "lift charge" (usually some kind of black powder). A different fuse within the shell of the firework — timed to ignite more powder (the "burst charge") and the color pellets mid-air — finishes the job.

Most fuses these days are not ignited by some brave thrill-seeker with a long match. Now, they're lit electronically, often with the aid of a computer program, by people who often have decades — sometimes generations — of pyrotechnic know-how behind them.

There's a nice start-to-boom graphic here.

"The black powder lift-charge is calculated to exhaust itself precisely when the slow-burning, time-delay fuse reaches the first compartment packed with light-producing stars and black powder. This happens when the firework is at the very apex of its upward flight," Shakhashiri explains. "Simultaneously the fuse sets off sound-producing explosives and detonates the stars, initiating color emission."

Ahhhh, the sounds of the explosions. Those are awe-generating, too. Though the family dog may think they're ow-generating.

(And remember: We see the explosion before we hear it, because light — more science here — travels almost a million times as fast as sound.)

The art behind the fireworks

If you make these missteps while setting New Year's resolutions, your plan could go up in smoke like these fireworks. (Photo: Aleksandr Simonov/

Fireworks aren't simply the stuff of blackboard calculations and periodic charts. A lot of care — not to mention a lot of research, a lot of trial and error and a lot of just plain deep thought — is put into what order the shells should be launched, the types of shells, the timing of the explosions, even the music that might accompany a fireworks spectacular. It’s very personal, very artful.

To truly touch the artistry of fireworks, though, you have to think more micro.

"The art of fireworks is the packaging," Stefan Bossmann, professor of chemistry at Kansas State University, says. "What the firework does depends on what's inside."

A simple example of how artistry comes into play in building fireworks: The stars closest to the bursting charge will ignite first, so those colors are the first you'll see. You have to know that. You have to envision it.

In the end, it takes both right and left brain — the scientist and the artist — to create a good show. And when they mesh, it's something that can enthrall and awe anybody.