system
Given the following post, respond as if you're commenting on Reddit:
human
The fact that our sun and moon are so close in size as viewed from our planet that we get to see eclipses amazes me. How rare is this in the universe, is there any 'reason' for it, and does this fact affect earth?

By 'reason' I mean something along the lines of "the earth is only massive enough to attract an object of some size, like that of the moon". I know this is incorrect, since it would depend on the mass of the moon, not the size. 
And as for affects on the earth, are there any other than the obvious (that we get to see eclipses)? I would assume that something interesting would happen with the tides during a solar eclipse, but I'm not totally sure.
gpt
It is purely a coincidence in time. The moon has been and continues to drift away from Earth, it was once considerably closer to Earth (Larger apparent size) and it will one day be considerably farther away(smaller apparent size). 

Tides are slightly higher when the moon is on the same side as the sun or opposite side as the sun.. just slightly though. This is because the moon is the primary tidal body to Earth.