Romans recycling, dinosaur colour, gravity mission

This week in the Planet Earth Podcast - how the Romans recycled glass, dinosaur colour, and what Europe's gravity mission tells us about ocean currents. Did you know that the height of the world's oceans can vary by as much as 200 metres? These huge differences depend almost entirely on very slight changes in gravity across the world. Sue Nelson goes to the National Oceanography Centre in Southampton to find out more. We also hear that even the Romans recycled glass. But were they being green, or did they have other reasons? Richard Hollingham goes to Norwich to meet the archaeologists... Like this podcast? Please help us by supporting the Naked Scientists