UPDATE:  SOLVED at 12:12 CDT by Bert

Are you ready to be frustrated today?  Of course you are!

This is your last chance before the next bonus riddle, which is Monday the 9th.  I know you’re ready, so I’ll jump right into it.  You’re looking for a thing:

This thing is generally thought of in the singular, but it’s complicated.  It is one huge thing, composed of many tiny things, which then manifests itself as two things.

This was known of by ancient man; but not understood.

It really terrified our ancestors.

We think of this as an Earthly phenomenon, although with telescopic advancements we’ve come to realize it isn’t.

This thing is not a cause; it’s an effect with a reason.

In an of itself, it is not important.  It does nothing.  It is a harmless “result”.

As unimportant as the result may be, the cause and the reason are important.

Did you get that?  I’m pretty sure you can slay this particular dragon with very little effort, so get your guesses in quickly.  You know where to find me…