Based on the combination of data taken 12 years apart by the NASA/ESA Hubble Space Telescope and ESA’s Gaia mission, astronomers have pinned down for the first time 3D motions of individual stars in the Sculptor dwarf galaxy, shedding new light on the underlying distribution of invisible dark matter that pervades the galaxy. The results are published in the journal Nature Astronomy. This image, taken with the Wide Field Imager camera on the 2.2-m...