What planet does the Dr Who monster "Rosie" come from?

I think she's basically humanoid and from a parallel planet to our earth, if I understand it correctly, though I didn't catch the name of the planet. She's not the ugliest of the monsters to have appeared on Dr Who, but far from the prettiest of his istants to date. And as far as I know all the other istants have been human, from Earth. What planet does it/she come from?