On Wednesday, humanity will be treated to a celestial trifecta: A supermoon (meaning it's relatively close to Earth), but also simultaneously a blood moon (it'll be orange or red), but also simultaneously a blue moon (the second full moon in one calendar month) will pass in the shadow of Earth, for a total lunar eclipse. It's going to be righteous.

But supermoon? Blue moon? Blood moon? Yeah, let's go ahead and pump the brakes on those terms, because the first was created by an astrologer, the second is highly subjective, and the third was only recently popularized by this-must-be-prophecy types.

First, some basics on the grand astronomical event. A total lunar eclipse is, of course, when the moon passes through the shadow of the Earth. But the Earth doesn't actually cast one super-delineated shadow. There are two components: the penumbra and umbra.