Radio galaxies 3C 75. Combined X-ray and radio image of the radio source 3C 75, caused by two galaxies (white dots) colliding. The radio part of this image (pink) was obtained with ground-based radio telescopes. The vast cloud of hot, X-ray emitting gas (blue) was observed with the Chandra X-ray Observatory (CXO) from Earth orbit. The huge gas cloud encompasses the galaxy cluster Abell 400, but in radio wavelengths, the only visible objects are the 3C 75 radio jets emanating from the colliding galaxies, which form a dumb-bell shaped object called NGC 1128. Abell 400 is some 300 million light years from Earth, in the constellation of Cetus.