Peepy, I agree with many of the posts that it does not really matter.
I am fairly intelligent yet never use a spell or grammer checker and often get things wrong. Worse still, I often place an extra word in a sentence for no reason whatsoever.
However, I do so enjoy when people argue and pick up on my grammer/spelling when in their silly squabble they make obvious mistakes themselves.
Not wishing to be argumentative but even your question is wrong. When I went to school earth as a planet was a name, hence Earth. With a small e, surely this means soil???
See my point?