An infrared/optical representative-color image of a massive galaxy cluster located 7 billion light-years from Earth. This cluster weighs as much as 800 trillion Suns. Galaxies with "old" stellar populations, like modern-day ellipticals, are circled in yellow; galaxies with "young" stellar populations, like modern-day spirals, are circled in blue. Images taken with the Infrared Array Camera on the Spitzer Space Telescope and the Mosaic-II camera on the Blanco 4-meter telescope at the Cerro Tololo Inter-American Observatory. The field of view is 4 x 4 arcminutes.