They are some of the most beautiful objects in the galaxy. Revealed in glorious colour and detail by the world’s great telescopes, they have become iconic images, blending science and art. They are the nebulae, giant clouds of gas and dust backlit by stars in the process of being born or dying. But are they really so colourful? Do these images show nebulae as we’d see them from the vantage point of a travelling spaceship, or have they been enhanced to wow the public?