[@poog the pig] I've researched it before and as I recall, Earth the planet was in fact named after dirt, but in a roundabout etymological way that probably took many years. It basically stems from a root that meant 'land' or 'ground'. 

Dry land was the world plants grew and people lived, farmed and worked on, and I presume the sea was something kind of external to that. For most people the entire world was a vast expanse of earthy ground, plus (unreachable) sky and (uninhabitable, empty) sea. Eventually people figured out that the Dirt is a speck of dust in an infinite void but by then the name had stuck.

That's for Germanic languages and possibly also Latin, anyway. Other languages might not have the connection.