A Second Confirmed Source of Gravitational Radiation

Astronomers detected for the second time gravitational waves from colliding black holes, opening a new window on the universe.

Scientists have directly observed gravitational waves, made by colliding black holes, show that gravitational waves can be detected regularly, confirming the start of a new, inportant era of astronomy.

Above, this illustration shows the merger of two black holes and the gravitational waves that ripple outward as the black holes spiral toward each other. Credit LIGO, T. Pyle

When you look up, you see the sky as it appears in light — electromagnetic radiation. But just over the past year, a new sky is becoming visible, humanity has begun to see our once-familiar sky as it appears in a different type of radiation, gravitational radiation.

Today, the LIGO collaboration is reporting the detection of GW151226, the second confirmed flash of gravitational radiation after GW150914, the historic first detection registered three months earlier. As its name implies, GW151226 was recorded in late December of 2015. It was detected simultaneously by both LIGO facilities in Washington and Louisiana, USA. In the featured video, an animated plot demonstrates how the frequency of GW151226 changed with time during measurement by the Hanford, Washington detector.