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The first detection of gravitational waves, announced February 2016, was a milestone in physics and astronomy, it was quickly followed by another find. Now teams working on the LIGO detector have just announced their third new detection. Gravitational waves are 'ripples' in the fabric of space-time caused by some of the most violent and energetic processes in the Universe. All three signals are thought to be caused by two black holes merging. This time the spin might give clues as to where the original stars formed.

Giant Methane Eruptions
Huge pockets of methane exploded in the region which is now the Barents Sea at the end of the last Ice Age. Could this happen again where ice-sheets are retreating? And, if so, what will be the impact on greenhouse gas concentrations?

Safer Gold Extraction
Many gold mines separate the precious metal dust from the rock using toxic substances like cyanide and mercury, but scientists at the University of Leicester have used rock samples from a gold mine in Scotland to prove they can do the job a different way, using a mixture of vitamin B4 and urea.

Genetics of Ancient Egyptian Mummies
Ancient Egyptian mummies give up their genetic secrets. Mitochondrial DNA from mummified remains show how much ancient Egyptians interbred with populations from Asia, Africa and Europe.

Picture: Nasa鈥檚 depiction of gravitational waves emerging from a black hole. Credit: Nasa
Presenter: Roland Pease
Producer: Fiona Roberts