First let me congratulate the LIGO team and its collaborators on the first confirmed detection of gravitational waves! It is a milestone for astronomy and astrophysics, and one well worth celebrating!

The gravitational waves that they have detected passed through the Earth on September 14, 2015 at 5:51am EDT, and are believed to have been generated by merger of two black holes that had been orbiting one another. Based on the data, this particular collision likely occurred 1.3 billion years ago between two black holes which were each around 30 solar masses in size. The gravitational wave that would have been generated would have contained three solar masses worth of energy by itself! It is one of the most energetic events in the Universe, and so it is not unexpected that the first detection would come from something like this.

As I have written before, one of the most significant obstacles detecting gravitational waves is the background noise. The effects of the gravitational wave are far smaller than the effects of such mundane events as traffic driving past or even people or animals walking too close to the detectors. However this signal was (almost) simultaneously detected at two experiments, located in Hanover, Washington and at Livingston, Louisiana. This double detection makes it far less likely to be anything of a terrestrial origin.

Aside from providing further confirmation of the predictions of general relativity, the ability to detect and analyse gravitational waves will provide important information for physicists in many different fields. The properties of these waves can tell us more about how black holes evolve and collide, or how galaxies interact with each other, and provide a better understanding any number of other astrophysical events that are too rare and too far away to be observed with traditional telescopes. This detection will certainly open up new areas of research in high energy astrophysics.

And so it would seem that after a century of studying the effects of Einstein's theory of general relativity, and about thirty-five years after the first hints of gravitational waves were observed in distant systems, the scientific community has finally managed to directly detect what even Einstein himself assumed would be undetectable. 

The official press release and more details on the discovery can be found here.