hey its not me

I think it's pretty impossible to say exactly who first named the planet 'Earth'. Actually, I really doubt one person really named it intentionally; rather it developed over time as part of the English language. Earth is Old English and German in origin, related to the Old Saxon 'ertha', the Dutch 'aerde', and the German 'erda'. Terra is a French and Latin word, and so isn't part of the 'Earth' etymology. I'm not really an expert on words and word origins, but it seems likely that people used Earth to mean 'land' and then it was the natural thing to refer to all the land and the planet. I tried to look up more specific details about the specific usage of the word over time, but even the Oxford English Dictionary (online) admits:

"Men's notions of the shape and position of the earth have so greatly changed since Old Teutonic times, while the language of the older notions has long outlived them, that it is very difficult to arrange the senses and applications of ...more