"...that's very big," Lucy said, in a tone that was most certainly awed. "I don't know much about how big planets are, but I know a lot about the size of countries..." She looked around her with new appreciation of the TARDIS. "...and of course a planet is even bigger." It would have been hard to imagine, a little police box, containing a whole world of sorts, if Lucy hadn't believed that magic could explain quite a lot of unlikely things. "It sounds to me like you and her have had had some adventures," she added, after a moment.