Bad taste, arsenic and blue skies ...

We explore the discovery that super hot, burning chillies can be used for pain relief; how holes in the asteroid belt show scientists how the planets got to be where they are; why things smell the way they do; the new clue into the cause of Alzheimer's; how our reaction to an unpleasant taste is the basis for our reaction to things we find objectionable; how arsenic exposure can be monitored in your toenails. Plus in 'Stuff and Non-Science', are the sea and the sky blue because they reflect each other?