The number of factors involved to make this happen is astronomical. Pun intended.
I propose the Scott equation for solar eclipses.
Because I want my name on sumpin dammit.
N = nr * fm * fp * na * L
nr is the number of rocky planets in the galaxy.
And I’m cutting out the gas giants for 2 reasons, one, in order for a shadow to fall on something you need a surface to fall on, and gas giants don’t really have a surface to speak of.
fm stands for the fraction of those rocky planets with a moon.
I’ve talked before about how rare and special our moon is, I mean just in our own solar system, only one other rocky planet has moons, and that’s Mars, which has two moons, Phobos and Deimos. But they’re really more like captured asteroids.
fp is the fraction of rocky planets with moons whose orbits cross the same plane as the planet and the star.
If the orbit of the moon never brings it between the planet and the star, no eclipse.
But the big one is na, or the number of moons that fit that angular alignment required to get a total solar eclipse.
In the case of Earth, the magic number is 400. The moon’s diameter is 400 times smaller than the sun and the sun is 400 times further away. How rare is this?
There is one other moon in our solar system that does this and that’s Jupiter’s moon Callisto due to its large size and vast distance from Jupiter.
Callisto is 179.3x smaller than the sun, and the sun is 179 times further from Jupiter.
The last variable, L is for length of time.
Drake included time as a variable because it’s logical to assume that the amount of time a species could be putting signals into space is finite.
I’m including it for the same reason.
Because the moon moves away from the Earth at a rate of 1.6 inches per year. Which means eventually, our moon won’t fully cover the sun anymore and it’ll be an annular eclipse.
And this slow progression away from the planet should be true of most moons due to orbital dynamics, so there is a finite length of time that a total solar eclipse would be visible.
How is it possible that one planet could experience not one but two utterly improbable but completely unrelated phenomena at the same time?
Maybe it’s more evidence for the rare-Earth hypothesis.
The idea that the conditions in place to create Earth and all life on it is so impossibly rare that we’re likely the only life in the universe.
Which slides into the anthropic principle which states that life on Earth is inevitable because the universe is compelled to create conscious life in order to observe itself.
This is the strong anthropic principle, the weak anthropic principal kinda goes the opposite direction, saying that we’re not that special but think we’re special thanks to selection bias.