Gravitational waves occur in space in a very fast ripple and the most outstanding thing is they are invisible. Over 100 years ago Albert Einstein came with some ideas of space and gravity so he discovered this fantastic ripples. These waves occur when planets and stars orbit each other causing ripples in space that move really fast.
“Gravitational waves are ripples in the curvature of spacetime that propagate as waves at the speed of light, generated in certain gravitational interactions that propagate outward from their source. The possibility of gravitational waves was discussed in 1893 by Oliver Heaviside using the analogy between the inverse-square law of gravitation and electricity. In 1905 Henri Poincaré first proposed gravitational waves (ondonesavifiques) emanating from a body and propagating at the speed of light as being required by the Lorentz transformations. Predicted in 1916 by Albert Einstein on the basis of his theory of general relativity, gravitational waves transport energy as gravitational radiation, a form of radiant energy similar to electromagnetic radiation. Gravitational waves cannot exist under Newton’s law of universal gravitation since that law is predicated on the assumption that physical interactions propagate at infinite speed.
Gravitational-wave astronomy is an emerging branch of observational astronomy which aims to use gravitational waves to collect observational data about sources of detectable gravitational waves such as binary star systems composed of white dwarfs, neutron stars, and black holes; and events such as supernovae, and the formation of the early universe shortly after the Big Bang.
On February 11, 2016, the LIGO Scientific Collaboration and Virgo Collaboration teams announced that they had made the first observation of gravitational waves (with the observation itself made on 14 September 2015), originating from a pair of merging black holes using the Advanced LIGO detectors. Since the initial announcement LIGO has confirmed two more (and one potential) detection of gravitational wave events. Besides LIGO, several other gravitational-wave observatories (detectors) are under construction.” https://en.wikipedia.org/wiki/Gravitational_wave