Free Download Suite for Photoshop. This set includes 20 abstract turn-based brushes that you can use in your design. I created a spin brush for using it to create galaxy texture in Photoshop. Creating outer space, textures, galaxies and so on will be easier if you use Photoshop brushes first.
These brushes are created using Twirl Filter, so if you want to create your own swim brush, check out these tutorials that teach you how to make giant waves in Photoshop.