Optical images of galaxies show quiescent disks of stars. However, these stars can die in violent explosions that throw gas completely off the galaxy’s plane in arcs that cool and fall back in a galactic fountain. This image shows the temperature distribution in an edge-on view of a Milky Way-like galaxy in a simulation. Hot gas (in yellow and red) is blasted from the disk in jets and bursts that then cools at it rises before returning to the galaxy.