Could a Siphon be used in orbit? Why do leaves change colour in Autumn? How is immunity passed from mother to baby through breastfeeding? Why do earthquakes happen away from plate boundaries? How do microwaves heat up food? We storm through your questions this week as well finding out how Twitter can be used to monitor moods around the world, how carbon dioxide can be converted back into a fuel, how biomarkers hidden inside ECG's can predict the risk of a repeat heart attack and how glowing bacteria can send secret messages! Plus, in Kitchen Science, we make flames without fire by making iron burn...