Pair of coalescing black holes

A pair of coalescing black holes, massive and dense monsters spiralling around each other. Just before merging into a single, even more gigantic black hole, they release a huge amount of energy in the form of gravitational waves - fluctuations in the fabric of space time.

This image shows a computer simulation of the gravitational waves that would ripple away from the black hole collision.

Gravitational waves were directly detected for the first time by the advanced Laser Interferometer Gravitational-Wave Observatory in 2015, and the discovery was announced on 11 February 2016.