And Terra just means dirt or ground in Latinate languages rather than Germanic ones.This is true only for common use. Any science sourcess call Sol 3: Terra, just like Sun is Sol, and Moon is Luna. While Sun is general name for any local star from the perspactive of specific planet, and Moon is a planet satelite.
But yes, in common language and in politics, Our planet official name is Earth. But mind that Earth means more like soil or ground rather than a planet.
So You are right but also wrong at the same time.