The dinosaur extinction 66m years ago was most likely due to a comet or huge asteroid crashing into Earth, but knowing that asteroids don't actually impact our planet very often, could this really be the entire story? Many scientists are now wondering whether some sort of cosmological event could have boosted the number of comets at the time, making such a collision more plausible. In a recent book, American cosmologist Lisa Randall points out that a huge disk of 'dark matter' – a type of invisible matter that is five times more common than 'normal' matter – could have been the cause. When sweeping past our solar system, such a disk would cause a tiny distress in space, cumulating to a flicker in the gravitational force that can push comets out of the solar system's Kuiper belt, or the Oort cloud just outside and send them towards the Earth. But can this theory be trusted? And are there any other cosmological events that could shed light into this matter? Mounting astrophysical and