Blog Post Image: NASA’s NuSTAR Helps Solve Riddle of Black Hole Spin

Two X-Ray Observatories are Better Than One. NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR, has helped to show, for the first time, that the spin rates of black holes can be measured conclusively. Image credit: NASA/JPL-Caltech/ESA/CfA/INAF (Click image to enlarge)