“Things need not have happened to be true. Tales and adventures are the shadow truths that will endure when mere facts are dust and ashes and forgotten.” -Neil Gaiman
Wherever we look in the night sky, we don’t just observe the background sources of light shining our way, but also the effects of all the matter in between those distant sources and our eyes. Since all of that inbound light needs to pass through a portion of the Milky Way on its way to our eyes, it’s vital that we understand how that light is distorted by our own galaxy. That means we need an understanding of the dust in our own neighborhood.
In the past, that meant using a variety of models, but for the first time, a 3D map of the Milky Way’s dust has been constructed. This will not only allow for a better calibration of distant objects — such as galaxies, supernovae and anything we’d use to measure dark energy — but it uncovers some surprises about the fundamental nature of dust itself.