She let out a contented sigh herself: one thing she and Renne had in common was there more motherly side, and that included affection.

Katara thought a moment. How to describe this? "It's more like thinking of the world as a round sphere: eventually, you can find yourself where you started from if you go fast enough. The higher or lower you go, the less sun you get and the colder it is. But yes, we have a top and a bottom."

Did that help? She hoped so: she wasn't the science person of their group: that was Billy.