So this isn’t about a scientific discovery by any means, but I did do a little bit of online research to discern the origin of the old expression that the Moon is “made of green cheese.” We’ve all heard it, and though I’m pretty sure that nobody has ever actually taken it as a fact (although when it concerns the Moon there never seems to be any shortage of crazy theories) I had to wonder just where it came from.

As it turns out, it’s the curiously uncanny remnant of a bit of snark that dates back to at least the 16th century — long before Apollo, spectroscopy, or even the first telescope.

Way back in 1546 ye olde English playwright and poet John Heywood wrote:

Ye fetch circumquaques to make me believe,
Or thinke, that the moone is made of greene cheese.
And when ye have made me a lout in all these,
It seemeth ye would make me goe to bed at noone.

Basically, “you’re trying to make me believe foolish things so you can treat me like a child.” (Heywood was a prolific proverbialist; some of his well-known quips include “haste makes waste” and “two heads are better than one.”) While Heywood probably didn’t personally invent the idea of a Moon composed of dairy products he was one of the first to get it in print, with the premise that only a fool would actually believe it to be true.

For some reason the saying stuck around long enough for people in later centuries to think that it was once considered an actual possibility or even a fact (a phenomenon related to hindsight bias or the Dunning-Kruger effect, possibly?) But in truth although the geological origins or chemical composition of the Moon weren’t themselves known until the 20th century nobody likely ever really thought the Moon was made of cheese.

(And especially not cheese the color of grass, Ecto-cooler, or The Incredible Hulk — the term “greene” was in Heywood’s time used to mean “fresh,” as in cheese that had not yet been properly aged. Since we know the Moon is around 4.5 billion years old, I’d say it’s anything but green!)

Sources: TodayIFoundOut.com and TheStraightDope.com 

PS: Not only is the Moon quite dairy-free, it also won’t ever turn green—despite what some silly viral social media posts like to claim. Just no.