You might already be aware of Horsetail Fall in Yosemite National Park (37.7291N, 119.6284W). It's a waterfall that's mainly known for the fact that, for a short period each year, the setting sun directly hits the water but not the nearby rocks, thus making it look as if the water were glowing, like a liquid version of fire (and even casting light on the nearby rocks), for about 10 minutes each day. People gather at particular spots in the valley below every year to wait for this.

Predicting when it will happen isn't a complex cosmo-geometry problem; it's just the same time of year that it's always been. Here is an example of a list of dates for 2019 that one photographer acquired somehow, and any variations from year to year are only on the scale of the changes in the dates of solstices and equinoxes. (The sun is at the right angle twice per year, in February and October, but there's nothing to see in October because there's too little water flowing.)

But it's occurred to me that the same kind of thing should also happen at night or twilight with a full or close-to-full moon. So, how would one predict when the moon will be at the right angle and in the right phase? I know there are programs out there that calculate the geometry for this kind of thing, but I don't have one or know how to use them...