UPDATE:  SOLVED by Steve at 12:20 CDT

All right!  We’re back to Saturday and the riddle.  Is everybody alert and ready for this one?  I’m thinking it will go fast, but I wanted to do this one.  I think you’ll find it fun, but hurry!

So, without further ado, your riddle:

Today’s riddle is an event.

Nobody on Earth witnessed the event; but almost everybody on Earth knows about it.

This event has been widely studied in modern times.

The answer to today’s riddle was the answer to an even bigger riddle.

Events like this one are frequent plot devices.

Although there is physical evidence for the event, it took a long time for scientists to realize what the evidence meant.

There is still controversy surrounding the event.

Did  you get that?  Do you know what the answer is?  Get your guess out quickly because I’m thinking this poor riddle will be shot down in about 6 minutes flat.  I’m in the comments.

I'll come out when Trudy stops threatening me!