15/18 How it was hoped we would be able to observe a feeding supermassive black hole in action. (R)
Maggie Aderin-Pocock explores our chances of finding life elsewhere in the universe. (R)
4/4 What may the digital future hold? Computers as tiny as the fluff in our pockets?
BBC Radio 4 Extra
1/2 Douglas Adams considers a global explosion in communication from a virtual world.
Andrea Sella returns to the Italian landscape of his childhood to see how it has changed.
BBC Radio 4
6/12 Looking at one of Fred Dibnah's favourite activities - restoring engines and chimneys. (R)
3/3 A portrait of the beauty and surprising wildlife of Scotland's Cairngorms National Park. (R)
Would you risk your life for a stranger?
BBC World Service
Listen live (BBC World Service homepage)
How the crowd is helping to track down extremists. Can twin lasers improve the 3D movies?
BBC News Channel