Yes, it is the same word. There is nothing "natural" about calling our planet "Earth" in a sci-fi setting unless you happen to speak English as your first language. "Erde" would be a hell of a lot more "natural" to me in reference to that big blue marble. Like the names of Mars, Jupiter, Saturn, Venus, Neptune, Uranus were used for the other planets, Terra "gave" hers to the Earth. Why would aliens in a sci-fi setting prefer a certain modern language over an older and neutral name?