Douglas Finkbeiner, Ph.D., Harvard University
Interstellar dust, the particulate matter in interstellar space, is of concern to astronomers because it makes background objects appear fainter and redder. As a site of most interstellar chemistry, it is interesting in its own right. Dust emission maps have long been used to estimate the total reddening caused by dust, integrated along the line of sight. These 2D maps are not adequate for reddening estimates within the Milky Way, where the object of interest may not be behind all of the dust. Using colors of 800,000,000 stars from the 2MASS and Pan-STARRS surveys, we can now infer the location of dust along each line of sight in about 30 distance bins, making a crude 3D dust map with - 5 arc minute angular pixels over ¾ of the sky. I will describe our publicly available map from 2015, and show improvements in the 2017 version. I will also argue that reddening-based dust maps are superior for certain cosmological applications because they do not include contamination from the FIR emission from large-scale structure. We anticipate that this approach to mapping and correcting for the effects of dust will be important for future large surveys, such as LSST.