Four of the galaxy clusters that will be studied by Frontier Fields: Abell 2744, Pandoras Cluster, MACS J0416.1-2403, MACS J0717.5+3745, MACS J1149.6+2223 NASA, ESA, and Z. Levay (STScI/AURA)

Four of the galaxy clusters that will be studied by Frontier Fields: Abell 2744, Pandoras Cluster, MACS J0416.1-2403, MACS J0717.5+3745, MACS J1149.6+2223 NASA, ESA, and Z. Levay (STScI/AURA)

Four of the galaxy clusters that will be studied by Frontier Fields: Abell 2744, Pandoras Cluster, MACS J0416.1-2403, MACS J0717.5+3745, MACS J1149.6+2223 NASA, ESA, and Z. Levay (STScI/AURA)