Why are plane and boat propellers in different places?

David wants to know, after looking at distant galaxies in the night sky, how long it took to create them. James Tytko took on the question with the help of the University of Cambridge's Public Astronomer, Matt Bothwell... Like this podcast? Please help us by supporting the Naked Scientists

Parasites have to come up with all sorts of tricks to evade the immune system of their hosts. But Kate wants to know, how do they know they've found the right place? James Tytko took her question on with help from Catherine Merrick, professor of parisitology at the University of Cambridge... Like this podcast? Please help us by supporting the Naked Scientists

Thanks to Cambridge University's Andy Wheeler for the answer! Like this podcast? Please help us by supporting the Naked Scientists

Rick wants to know why the Canada geese he's been observing, who are preparing to migrate for the winter, are honking so incessantly while flying in formation. Viola Ross-Smith from the British Trust for Ornithology was on hand to help James Tytko with the answer... Like this podcast? Please help us by supporting the Naked Scientists

Van writes in with, 'A friend is encouraging me to take a cancer screening test that screens for many different cancers. A review of one test says: "While overall it picks up 90% of stage 4 cancers, it only detects an average of 17% of stage 1 cancers. Yet it is being touted as a test that can detect cancer early." Are these tests worthwhile?' James Tytko took on the question with the help of Professor Rebecca Fitzgerald, Founding Director of the Early Detection Institute at the University of Cambridge... Like this podcast? Please help us by supporting the Naked Scientists

If dinosaurs hadn't been wiped out by a mass extinction event, would there have been room for humans to grow into the successful species we are today? That's what Colin wants to know, and James Tytko has promised to find the answer. He spoke with Dr Charlotte Kenchington from the University of Cambridge's Department of Earth Sciences... Like this podcast? Please help us by supporting the Naked Scientists

Pamela wants to know whether the distribution of chemical isotopes is the same on other planets as it is on Earth. Take carbon, for example, 99% of which is carbon-12 on Earth while 1% is carbon-13? To find the answer, James Tytko asked Xander Byrne from the University of Cambridge's Institute of Astronomy... Like this podcast? Please help us by supporting the Naked Scientists

David wants to know whether the intricate and varied spiders' webs seen in nature are a product of arachnid instinct, or something that is cultivated across their life. To get to the truth, James Tytko sought out spider expert Professor Sara Goodacre from the University of Nottingham... Like this podcast? Please help us by supporting the Naked Scientists

Jim writes in to say, 'Sometimes when I pinch near my knee, I will feel a tingling or tickling sensation behind one of my shoulder blades. What's up with that?' James Tytko found him an answer, with help from neuroscientist Dr Mark Hoon from the NIH... Like this podcast? Please help us by supporting the Naked Scientists

Oscar asks whether the snail stuck on the inside of his car wheel while he went for a drive would have felt the effects afterwards. Jon Ablett from the Natural History Museum helped James Tytko with the answer... Like this podcast? Please help us by supporting the Naked Scientists