and the stars look very different today

The ever-discerning Kottke gives us a nice primer on the first confirmed, cautious measurement of gravitational waves, ripples echoing out across the Universe, only approaching a vanishingly small but just detectable undulation from what would seem to be the most violently explosive of events—the dangerous waltz and collision of a black hole and its dance partner.
This kind of carnage of the dance-floor, after indirect sightings and a needful component of the Theory of General Relativity was first proffered a century ago (there’s a nice vintage newspaper clipping at the link above) that although some measure of confidence was withheld and no one knew whether we might have to return to the drawing-board, produced an explosion so powerful as to be felt across space and time by a pair of super-sensitive seismographs. One possible inference of this space-quake is the existence of a heretofore hypothetical massless particle called provisionally the graviton. The particle responsible for imparting mass is thought to have none itself because gravity appears to have an infinite range, and objects tug on each other no matter how far apart.  What do gravitational waves mean to you?  The Universe is bumping us apart and pushing us together with these wave fronts all the time but we cannot experience them as our frame of reference is compressed and expanded to an equal degree.