What Makes Fireworks So Colorful?

Everyone knows that fireworks are just carefully engineered explosions. But most explosions never leave the ground, much less light up the sky with dazzling color. Here's how these bundles of gunpowder create their scintillating light shows.

3, 2, 1, Blast Off!

Fireworks create their magic by including not one, but two explosions: one to get it off the ground, and one to create the designs. Pyrotechnicians first light a short-burning fuse, which ignites gunpowder packed in the bottom of the firework and causes it to shoot into the sky.

A second fuse, known as a "time-delay fuse," lights at the same time as the short-burning fuse, but it's carefully designed to ensure the firework achieves a certain altitude before its spark reaches the next compartment. That compartment is filled with a mix of gunpowder and "stars," the flammable spheres responsible for the points of light you see when a firework explodes.

Color Science

Coating these spheres with different metals gives them different colors: strontium makes them red, calcium makes them orange, and barium makes them green. Burning these metals excites their electrons and makes them release energy in the form of light. The amount of energy released is unique to each element, so the color a metal produces is like its own chemical fingerprint — a specific wavelength of red will always be identifiable as strontium, for example. The colors are so reliable that scientists even use them to determine the chemical composition of distant stars. 

Written by Curiosity Staff July 1, 2016

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