Fantastic ligting and colours! the nebula is both original yet realistic with it's stretched out pattern and there's a nice parrallel movement going on which is made more interesting by the oppositing direction of the rings
Not so bad a scene at all! The colours are quite enjoyable, too. However, I do have some suggestions. Firstly the nebulae and the stars (and the planetary edges/interaction with the scenery) seem particularly rough, some soft glow (perhaps controlled with screen/overlay/soft overlay mode layers) over it could work quite well here to blend things together more seemlessly without losing detail. Perhaps the large planet could cast a light shadow on the rings, too (this would also further highlight the interaction of light in front of it from the closest apparent planet). The distant nebulae also seem a little flat, and some slight contrast work, whilst keeping it less prominent than the rest of the nebulae, could improve the depth. I also suggest you upload a slightly larger resolution next time - perhaps 1024×768 at least. Otherwise, quite nice!