The earth's satellite - our moon - has a profound effect on so much down here on earth, from the tides (you'd hardly notice them without it) to the length of days (much, much shorter) and the seasons (hugely variable as earth's axis would tilt enormously).
In addition, by that freak of nature we call chance, our moon is just the right distance from us for our shadow to cover its surface (lunar eclipse) and just the right distance from our nearest star to occlude the sun completely at a total solar eclipse.
Just think of the impact that must have had on our ancient (and not-so-ancient) ancestors. It's little wonder that the Moon has had such a profound cultural, historical and psychological impact. We still call one of the days of the week 'Moon-day' for goodness sake!
There's a whole lot more that could be said but for now, let's just let the Moon itself do the talking...