Pyrotechnics

Tonight around the US, fireworks will be launched to celebrate July 4th, our day of independence.  In the historic city of Boston, Massachusetts, 20 thousand pounds of fireworks will be launched in a dazzling display of color and sound.  So I was wondering how this festive occasion compares to the radiance of a single nondescript star.

A typical firework has about 200 grams of black powder (or other lifting charge).  Black powder when burned typically releases 3 Megajoules per kilogram of energy.  If we estimate about 20,000 fireworks this gives a grand total of 12 billion joules.

Now the power of a typical star, such as the Sun is about 1026 Joules/sec.  So a single star burns up the energy of the entire Boston fireworks show in about 10-16 seconds.  As an example of how short a time that is, it takes a ray of light about 100 times longer than that to traverse the length of a single human cell.

So today, wherever you are, enjoy some real fireworks.  Happy July 4th!!!

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