Earth is the only planet whose name in English is not derived from Greco-Roman mythology. Because it was only generally accepted as a planet in the 17th century, there is no tradition of naming it after a god. (The same is true, in English at least, of the Sun and the Moon, though they are no longer generally considered planets.) The name originates from the 8th century Anglo-Saxon word "erda", which means ground or soil and was first used in writing as the name of the sphere of Earth perhaps around 1300. As with its equivalents in the other Germanic languages, it derives ultimately from the Proto-Germanic word "ertho", "ground", as can be seen in the English "earth", the German "Erde", the Dutch "aarde", and the Scandinavian "jord". Many of the Romance languages retain the old Roman word "terra" (or some variation of it) that was used with the meaning of "dry land" as opposed to "sea". The non-Romance languages use their own native words. The Greeks retain their original name, "Γή" "(Ge)".