Maybe it was a trick of the light or a strange cloud, or just not enough sleep. A couple nights ago I could have sworn that thin crescent moon flickered.

Which led to an interesting question - what conditions could make the moon flicker?

Of course, there are all kinds of interesting consequences. I know we have a couple eclipses each year, and the moon has phases, but overall, we take the steady, ethereal glow of the moon for granted.

By flicker, I mean off and on within seconds to an hour. The phenomenon must be observed wherever the moon is visible.

I realize the physics of moonlight make this hard, so a habitable Terra-like planet in another system is ok. The moon just needs to be large enough to be extremely obvious and an important part of the night sky, so that its flickering would be impossible to miss. I'd especially like it if this were a recurring event, maybe even a regular feature of the night.