 The wave information does not tell us in which direction it came from, because each interferometer is a whole sky monitor, with very little directional information, but having two detectors does give us some directional data. For example, if the wave came in parallel to the line between the two sites, the signals would have registered at the exact same time. If the wave was perpendicular to the line, we would have seen a time delay of 10 milliseconds, because the wave travels 3002 kilometers through the earth at the speed of light. What we detected was a wave that came in at an angle that caused a delay of 6.9 milliseconds. The dotted line represents the distance the wave had to travel for a piece of it to reach the Hanford interferometer. A little trigonometry gives us the angle. Of course, this angle gives us a circle of possible directions. Interferometers are most sensitive to waves that come in perpendicular to their two arms. Sensitivity drops off as the incidence direction departs from the perpendicular. The curvature of the earth gives the two LIGO interferometers an angle difference of around 27 degrees. This creates slight amplitude and phase inconsistencies across the two detectors that enable a narrowing of the probabilities to a smaller portion of the sky. Here are the most probable directions as seen from earth. The best way to increase the accuracy of our directional findings is to use a third gravitational wave detector to triangulate the source. Several are under construction or being upgraded to do just that. There is a map of current and future gravitational wave observatories on the earth's surface. One of the greatest opportunities we have now that we can detect gravitational waves will be the ability to observe events that happened before light was traveling across the cosmos. The first 380,000 years after the Big Bang are known as the Dark Ages. As you can imagine, there is a lot of guesswork that goes into figuring out what happened during that period in the universe's history. Gravitational waves created within the Dark Ages may help us untangle that mystery. More time will tell.