We are made of exploding stars: from the iron in our blood to the calcium in our bones. It all comes from supernova explosions, and now researchers can look inside the center of one. Cassiopeia A was once a star with a mass over eight times greater than our sun. Over 300 years ago, it died, creating an inferno, and NASA has been shifting through its radioactive ashes using the NuSTAR space telescope. The telescope array generated the first map of radioactivity; Nature published NASA’s findings on Wednesday, as reported by CNN. To better understand how scientists study supernovas check out Big Think‘s interview with Ray Jayawardhana, an astrophysicist at the University of Toronto and the author of Neutrino Hunters: The Thrilling Chase for a Ghostly Particle to Unlock the Secrets of the Universe.