When it comes to technique I've used a base photograph of some swirling paint, digitally painted on top of it using the digitized Edvard Munch brushes and then pixel sorted it in After Effects.
See below for the process.
2. Distorted the image I had using displacement.
3. Photographed some swirling paint that had a similar composition.
5. Added the colours from the first digitally painted layer. Also added "stars" by using the brushes and then masking them to make them more "scattered" like tiny stars.