Astronomers have constructed the first detailed 3D map of the properties of cosmic dust in our home galaxy. For their map, the astronomers used 130 million spectra from ESA's Gaia mission, results from the LAMOST spectral survey, and machine learning. Dust makes distant astronomical objects appear more reddish and dimmer than they really are, so the new map will be an important tool for astronomers to make sense of their observations. The study has also revealed unusual properties of cosmic dust that will lead to further research.