Cosmic microwave background research, ALMA-HST image. Combined observations by the Hubble Space Telescope (HST) and ALMA (Atacama Large Millimeter/submillimeter Array) were made of this galaxy cluster (RX J1347.5-1145), which is 5 billion light years from Earth. The HST observations in visible light are in yellow, with the ALMA radio observations in blue/purple. These observations reveal a phenomenon called the Sunyaev-Zel'dovich (SZ) effect, where high-energy electrons in the galaxy cluster have an effect on the photons that form the cosmic microwave background (CMB). The observations formed part of the Cluster Lensing And Supernova survey with Hubble (CLASH). Image published in 2017.