Cygnus A galaxy. Coloured Chandra X-ray telescope image of the active galaxy Cygnus A. This galaxy exists in a relatively abundant intergalactic gas medium (red) that is hot enough to emit X-rays. Expanding material from Cygnus A, thought to be fuelled by a central black hole, creates a cavity (yellow) in the gas. The gas is compressed at the cavity boundary (dark orange line), causing it to emit high-energy X-rays. Two powerful jets emanate from the active core (white), and are slowed by the gas, terminating at the cavity boundary as X- ray hot spots (yellow, upper right and lower left) some 600,000 light years apart. This galaxy is around 700 million light years from Earth.