Artificial Noses, Aeroplane Toilets and Big Brains

Where does the waste from an aeroplane toilet go? And could you ever really get stuck to one when pressing the flush? Do we have bigger brains than 500 years ago? Why are planets spherical? We tackle all of these questions this week, as well as finding out that researchers have created an artificial nose even more sensitive than a dog's. Plus we'll discover why onions make your eyes water...