You’ve heard this before.  But sadly, most of you still could not pass the corresponding chemistry quiz.  And so we present, as a refresher course, another helping of heavenly hellfire.

OK, you may recall from high school science class that cellular energy is known as ATP, or Adenosine Triphosphate.  It’s common to all living things.  But there’s a second and much more RARE substance known as Luciferin.  When it mixes with ATP, it sets off a curious set of reactions.

First, it creates Luciferyl Adenylate and Pyrophosphate. What’s that, it’s too hard to remember?  OK, here it is as a chemical equation:

Luciferin + ATP → Luciferyl Adenylate + PPi

But wait, there’s more. As soon as it is produced, the Luciferyl Adenylate turns right around and reacts with Oxygen to create Oxyluciferin and Adenosine Monophosphate. Which, in chemical shorthand, is this:

Luciferyl Adenylate + O2 → Oxyluciferin + AMP

But here’s the really wicked part: that second reaction is what your chemistry teacher would have called “exothermic.”  It’s a reaction that gives off energy, in this case in the form of light. In wavelengths of between 501 and 670 nanometers.  Which the human eye sees as colors ranging from pale yellow to reddish green.

Oh the chemical irony!  Luciferin, named for the Lord of Darkness, causes a reaction that creates…a celestial glow!!

And where does this minor miracle happen? Right in your yard, of course. Or, more specifically, in the abdomen of an insect your biology teacher would have called Pyrophorus noctiluca. This little fella flies around with a belly full of Luciferin. Each time he takes a breath, some Oxygen reaches the Luciferin and produces a short, unmistakable burst of heavenly light. Then, as the insect breathes out, the light goes out. And so on…

You can see it for yourself, in your own homemade biochem lab. Just go outside this weekend and catch a firefly on your hand. He will invariably climb up onto the highest point. And then, before he takes off, he’ll just sit there, getting ready.

Breathing in, and out.

Blinking on, and off.

In, out, on, off.

It’s simple.  It’s miraculous.  It’s wicked.