On Independence Day here in the States, the folks over at National Geographic have put together a timely video an what makes fireworks function. What makes them fly to the perfect height? Why don’t they explode on the way up? And how do you get all those great bursts of color? Answers to these questions and more are explained in their “I Didn’t Know That: Fireworks” short video
The basic firework recipe is flash power, a potent form of gunpowder. It’s a mixture of potassium perchlorate and aluminium. These ingredients are mixed together in seven kilo batches and a small sample is ignited to make sure it has the requisite brightness.
There are two perfectly formed rings of stars. An central ring and an outer ring. The outer ring are made of stars of a slightly larger size. Therefore they’ll be heavier and when the burst in the middle ignites these stars and blows them in the er circle formation, the inertia of the heavier, larger stars will travel further. Thus in the sky you’ll see one small ring and then a larger ring around it.