The galaxy cluster called MOO J1142+1527 can be seen here as it existed when light left it 8.5 billion years ago. The red galaxies at the center of the image make up the heart of the galaxy cluster.
This color image is constructed from multi-wavelength observations: Infrared observations from NASA’s Spitzer Space Telescope are shown in red; near-infrared and visible light captured by the Gemini Observatory atop Mauna Kea in Hawaii is green and blue; and radio light from the Combined Array for Research in Millimeter-wave Astronomy (CARMA), near Owens Valley in California, is purple.
In addition to galaxies, clusters also contain a reservoir of hot gas with temperatures in the tens of millions of degrees Celsius/Kelvin. CARMA was used to detect this gas, and to determine the mass of this cluster.
Image credit: NASA/JPL-Caltech/Gemini/CARMA