World's most powerful telescope launched into orbit

The world's most powerful telescope has been blasted off into space by a European Ariane Rocket from French Guiana. With its huge gold-plated mirror, the James Webb Space Telescope aims to see deeper into space than ever before, to picture the very first stars. We speak to Thomas Zurbuchen, NASA's head of science. Also in the programme: How climate change is driving reindeer from their feeding grounds; and our correspondents look back at some of this year's biggest stories. (Image: Lift-off of an Ariane 5 rocket carrying NASA's James Webb Space Telescope. Credit: Epa/JM Guillon/Esa handout)