Gravitational waves have been detected for a second time. These waves are ripples in the curvature of space time, predicted by Einstein in his General Theory of Relativity in 1916. Back in February, the Laser Interferometer Gravitational-Wave Observatory (better known as LIGO) announced that they had detected the signal of gravitational waves from the collisions of two big black holes. The detection in February was the first observation of these waves, and confirmed General Relativity. This week, LIGO confirm a second detection. BBC Science Correspondent Jonathan Amos explains what is new about these new gravitational waves.

We know more about the surface of the moon than we know about the ocean floor. Admittedly, the sea is much more dynamic, the scene of many chemical and biological processes, about which scientists would like to learn more. This week, cartographers meet in Monte Carlo, to discuss their plan to map the ocean floor by 2030. Roland Pease reports on the ocean-mapping options.

The spoonbilled sandpiper is standing on the edge of extinction, but in good news, Adam hears about of a clutch of eggs laid not in their native Russia but in Slimbridge in Gloucestershire. BBC producer Andrew Luck-Baker visited the Wildfowl and Wetlands Trust’s population back in April, and describes these birds to Adam.