Nebular draws dreamy clouds of light which vary in appearance from a rippling silky liquid to streamers, smoke, and auroras. This is all produced from fractional Brownian motion (fBm), and is animated to produce a smoothly evolving image.
Nebular allows a wide range of configuration to allow its appearance to be tailored to your taste: the number of colours, their vividness, the amount of detail, and the speed at which the animation moves.