How do fireworks work?

📓 The short answer

A series of explosions launch the firework into the air and then cause it to burst into colorful displays. The vibrant colors are produced by metal atoms that release light when their electrons get excited by the heat.

📚 The long answer

Whether you "ooh" and "aah" at fireworks shows or would rather they not make such a ruckus, the science and mechanics behind them are pretty interesting!

There are many types of fireworks, but I'm going to focus on aerial fireworks. Aerial fireworks, the ones used in big shows, are shot off into this sky before they explode into bright colors.

The key ingredient of fireworks comes from black powder, a type of gunpowder. When black powder is ignited, it explodes!

In a nutshell, an aerial firework has three main explosions::

🧨 Lift charge: A layer of black powder at the base of the firework. This first explosion sends the firework shell into the air.
💥 Burst charge: A pocket of black powder inside the shell of the firework. This second explosion causes the firework stars (see below) to explode and go flying through the air.
🎆 Stars: Numerous small pellets that create bright, colorful lights when ignited. This final explosion is responsible for the dazzling affair.

A diagram of a firework showing from bottom up: a clay base, a lift charge layer (black powder), a lit fuse, an unlit time delay fuse, an aerial shell containing a burst charge (black powder), and stars, all held within a mortar container.

In more detail, here are the steps of how a firework goes off:

Step 1: The fuse is lit, giving time for the pyromaniac to move to safety.

Step 2: The fuse sets off the lift charge. This does two things: It sends the aerial shell flying up into the air, and it lights the time delay fuse. The mortar guides the shell straight up.

A diagram of a firework after the lift charge has exploded showing from bottom up: the explosion of the lift charge, the lit time delay fuse, and the aerial shell being sent up through the mortar

Step 3: The time delay fuse is there to (you guessed it) add a time delay before the aerial shell explodes in the sky.

Step 4: Once the shell is high in the air, the time delay fuse ignites the burst charge.

A diagram of the aerial shell with the burst charge exploding and the stars being sent off in all directions

Step 5: The burst charge explodes the aerial shell, sending the ignited stars flying in all directions.

Step 6: The stars themselves explode and create vibrant, colorful lights in the sky.

A three-part act: The shell ascends, the shell ignites, the stars explode into colorful lights.

How do fireworks get their color?

In essence, fireworks work thanks a series of well-timed explosions. But how do they create dazzling colors?

A photo of many different fireworks going off with many different colors. — "Australia Day 2013 Perth 39" by Kaoz69 is licensed under CC BY-SA 3.0.

Fireworks get their colors from how different metals react to heat.

The intense heat from the star's explosion excites the electrons in the metal atoms. When electrons are excited to higher energy levels, they become unstable and quickly return to their original energy levels. As they drop back down into their ground state, they release the excess energy as light. This video clip does a great job of explaining this phenomenon in greater detail.

Different metals have different energy gaps, which correlates to the emission of different colors. Here's a breakdown of which metals are responsible for which colors in fireworks:

Color

Metal

🔴 Red

Strontium, lithium

🟠 Orange

Calcium

🟡 Yellow

Sodium

🟢 Green

Barium

🔵 Blue

Copper

🟣 Violet

Potassium

🌟 Gold

Charcoal, iron, lampblack

⚪ White

Titanium, aluminum, magnesium

For making it this far in the newsletter, you deserve a little treat. Here's my personal favorite fireworks video of the time of when all the fireworks planned for a Fourth of July show accidentally went off at the same time (don't worry, no one was harmed).

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Thanks for reading this week's newsletter! If you have any thoughts, questions, or favorite GIFs, my inbox is always open. Just hit reply to send me a note! :)

All my best,

Caitlin

Click here to read five facts about Caitlin

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📖 Book of the week

Citizen Hobo: How a Century of Homelessness Shaped America by Todd DePastino

This book traces the history of homelessness in America from the late 19th century to the present day. Through in-depth research and personal narratives, he illuminates the stories of hoboes and tramps and their impact on the country. DePastino offers an insightful perspective on homelessness, showing how it is intertwined with issues of poverty, inequality, and social justice in American society.

It's a pretty dense, academic book, but I found it to be an illuminating look at the history of homelessness in the United States and how it has impacted culture.