BBC Sky at Night Magazine
I am an amateur astronomer and this weekend I visited my son and his family. My five-year-old grandson, Reuben, was telling me about the ISS and, somehow, we touched on black holes. He was intrigued by your story of the nearest discovered black hole (‘Nearest stellar-mass black hole discovered’, Bulletin, July issue) and that while the irregular motion of the double star led to its discovery, it didn’t explain the
motion. The mystery remained. He would like to know two things. First, is it possible that the star motion is explained by a second nearby black hole? And second, what would happen if two black holes met? Can you help? We might have an astronomer on our hands! Prof Roy Sandbach, via email Astronomers used computer simulations to recreate the wobbling motion of the stars and a black hole in orbit was the best explanation. When two black holes meet they merge together, creating massive ripples in space time known as gravitational waves, which astronomers first ‘heard’ back in 2015. – Ed.