These four dwarf galaxies are part of a census of small galaxies in the tumultuous heart of the nearby Perseus galaxy cluster. The images, taken by NASA's Hubble Space Telescope, are evidence that the undisturbed galaxies are enshrouded by a "cushion" of dark matter, which protects them from their rough-and-tumble neighborhood. Credit: NASA, ESA, and C. Conselice and S. Penny (University of Nottingham)
