Scientists using the Laser Interferometer Gravitational-Wave Observatory (LIGO) have detected gravitational waves, which were predicted by Albert Einstein in his general theory of relativity. The source of the waves was a pair of black holes that collided about 1.3 billion years ago. The waves formed distortions in space that are extremely small when they passed the earth about five months ago.
Read more at Space(dot)com, Science, CNN, Science Alert and The Telegraph.
I had previous run across the subject of gravitational waves in another Space(dot)com article, which reported the discovery of "B-node" polarizations in the cosmic background radiation, which are believed to have been in turn caused by gravitational waves generated during the inflation period of the Big Bang. However, that discovery did not detect the waves themselves.