Nevis Laboratories presents Science-on-Hudson Professor Frits Paerels, Columbia University The Universe is full of dust, produced by stars. As in your house, so in astrophysics: the dust is a nuisance. It literally obscures and distorts our view of distant objects. But unlike what happens in your house: dust also provides us with totally unique opportunities to see echos of past events (supernova explosions in the Galaxy), and find out things about them that were lost to the historical record. I will discuss an application of this idea that may allow us to pinpoint the locations of gravitational wave sources that are now being discovered, but cannot be located in the sky. That will make them important for applications such as precision cosmology and the fundamental physics of gravity.