The Moon can block the Sun completely during a solar eclipse because the Sun is far, far away. Is it then pure coincidence that the Moon almost completely fits the Sun’s outline, or could we’ve had solar eclipses with a much smaller Moon, thus blocking the sun only very partially?

Question

Title.

In: Physics

Answer 1

Yes it is a coincidence.

The sun is roughly 400 times larger than the moon.

But it is also 400 times further away.

So, to us on the ground, they happen to look the same size and you can get a perfect total solar eclipse.

If the moon was smaller, or further away, it wouldn’t be able to completely cover the sun.

The moon is actually moving away from
The earth right now by a couple centimeters a year on average, so in several Tens of thousands of years is possible that the moon will no long be able to totally eclipse the sun from earth