So I just saw the YouTube video someone posted that showed nuclear reactors starting up, and the first thing I noticed was that they all glowed a very bright, pretty blue. I’m probably an idiot, but I was honestly expecting green, because of many years of dramatized depictions in popular media.

These are probably dumb questions, but:

1. Why is it blue? As in, what’s actually glowing in there, and why do we see it that way?

and

1. Why do all the movies and comic books and video games go with green instead? Where did that come from?