It's estimated that by 2030 more than 100 thousand satellites are likely to be buzzing around in low-Earth orbit – and the implications of that for our dark skies is potentially significant. We hear from the Executive Director of the non-profit network DarkSky International. Also, is our environmental future written in the past? Paleo-conservation could be the answer to how we adapt to the adverse effects of climate change; and in Stockholm, engineers and builders are hard at work creating an entire city district in wood – from apartments to office towers. So, what's the advantage to building in timber?