Wow, that's really neat! I was looking around for something like this recently; my space based shooter would look great with an animated nebula in the background...especially since the working title is 'Nebular Drift'
Any way to get it moving?
I have no idea
If you are mathematically minded/genius you could implement
Density Wave Theory
Or you could try to cheat with extra canvases. Create a random number and plot the point/star on a different canvas depending on this number and then rotate the canvases at slightly different speeds. Not sure how it would look but would probably be better than rotating the 1 canvas.
Link to gif -
(7mb & recorded at 10fps)
Multiple canvases destroys the galaxy.