The Science Behind the Art of Fireworks

Fireworks are a beautiful sight, but few people are aware of the science behind them. The average firework is made up of a mortar with a charge placed at the bottom made up of gunpowder. On top of the charge sits a structure called the “shell” which contains all the material that produces the actual firework display known as the “stars”. When a fuse is lit, the charge ignites creating an explosion that propels the shell upwards. The shell in turn has a timed fuse that ignites at a certain height. This fuse detonates a secondary charge attached to the shell called the “burst charge”. When the burst charge explodes, it disperses the ignited stars in the shell creating the colored lights we admire during celebrations.
 
To generate bursts of different colors, different elements are used in the fireworks. The principle is that when an element is heated, its atoms absorb this energy and then release it as light of a wavelength characteristic of the element. To create a red color, the firework’s stars are made from the element strontium. For orange, calcium is used. For yellow, green, and blue, sodium, barium, and copper are used, respectively. To obtain a purple color, strontium and copper are mixed in the shell, and to generate the color silver, magnesium and aluminum are used. To produce white light in the firework, magnesium and aluminum are combined with titanium.
 
This, of course, is just a general explanation of the science behind fireworks. There are a lot of nuances to fireworks such as the sounds they make (booms, crackling, or whistling), and the force and timing of the explosions and their directionality with regards to the components of the shell in order to create random or specific patterns in space, also including effects such as strobe or sparks.
 
The video below shows a firework display in Germantown, Maryland in 2013.