On this weeks Ask the Naked Scientists we investigate the science of sat-navs - how do they work? And how do they know where our speed cameras are? We find out why it's so hard to get a signal on our mobile phones when we're underground and whether the light from stars changes as it reaches our eyes. We also find out why insects aren't stung by stinging nettles, reveal if water really does flush the other way in the Southern hemisphere and find out the real reason why we can't use our mobiles on planes. Like this podcast? Please help us by supporting the Naked Scientists
