Size matters : for a lunar eclipse

So, in thursday / friday, there is a total lunar eclipse to be seen in the UK. They are very cool, and I would recommend if you are nearby and have insomniac leanings, you take a look.

But more importantly, is it just me who thinks these things, or is it remarkable that total eclipses happen at all ?

Thin about it : the earth has to be just the right size to cast a shadow across the moon so that it just covers the whole moon. Same as  a solar eclipse : the moon is just the right size to cover the sun and leave a little bit ( the shiny rim with all of that marvellous activity ) showing.

I guess if I do the maths, I will find that the distances are large enough that the moon and earth could be quite different sizes, and we would still see the effect, but these things concern me. Why are they ’just’ the right size for these phenomenon to happen ?

Whatever the reason, I’m kind of glad that we get a chance to see such terrific events.