1. How Metals Inside Fireworks Create Colors
Inside a firework shell, there are small pellets called "stars." These stars contain metals that are responsible for creating color. When these metals burn and become very hot, they emit light of a specific color. The color depends on the type of metal being burned. [1]
For example, the metal sodium produces yellow light. The metal strontium creates red light. Barium makes the light green, while copper produces a blue-green color. [1] You may have seen an experiment in science class called the "flame test." The principle behind firework colors is the same as this experiment.
2. How the Arrangement of Stars Makes Shapes
Inside the firework shell, the small pellets called "stars" are arranged in a precise order. [2] When the shell bursts open in the sky, these stars fly out all at once. They spread out while glowing. [2]
The shape of the explosion depends on how the stars are arranged. For instance, the "Peony" shape spreads out in a circle. The "Chrysanthemum" shape spreads out while trailing sparks. [2] By changing the arrangement, many different patterns can be created. [2]
3. Why Most Fireworks in Japan Are Round
Most fireworks seen in Japan are round spheres. However, in places like Europe, you can also see fireworks that are shaped like tubes or cylinders. [3]
The round shape is resistant to the strong impact during launch. [3] Additionally, the force inside the shell acts equally in all directions. This means the firework spreads out into the same round shape no matter where you view it from. [3]
4. How to Find Color Combinations in Firework Photos and Videos
Try looking at photos or videos of fireworks. See if you can find red, yellow, green, and blue colors. If you find them, check this article again to see which metal is likely creating that light.
Do not try to burn metals at home to test this. It is dangerous.