Centaurus A galaxy. Hubble Space Telescope (HST) image of the centre of the active galaxy Centaurus A, which is thought to house a massive black hole. Centaurus A is a large elliptical galaxy which collided with a smaller spiral galaxy millions of years ago, sparking a huge burst of starbirth activity. Large areas of young blue stars are seen on either side of the dark lane of dust. This dust is thought to be the remnant of the smaller galaxy which Centaurus A swallowed. Centaurus A is also a powerful emitter of radio waves powered by its black hole. It lies 10 million light years from Earth in the constellation Centaurus.