IN THE search for what triggers ice ages, everything from space dust to Earth’s wobbly orbit has been blamed. But a much bigger mover and shaker could be to blame for these icy spells – the Milky Way itself.
Our Solar System rotates around the Milky Way’s core at twice the speed of its four spiral arms, meaning we pass through each of them on our journey round the Galaxy. But the trip is made perilous by cosmic rays, deadly high-energy particles that stream out from exploding supernovae. The Milky Way’s arms are peopled by dense clusters of short-lived stars going supernova and belting out these cosmic…
