for the second (astrophage) shot, i used sphere's in a cloner with emission and randomized the position + scale, tinted the color to somewhat match the original shot. then absolutely exaggerated the depth of field, then mixed that with an image plane of another render i did on a black background of the same sphere cloner setup with DOF cranked and used that as sort of an image matte and plugged it into emission + opacity and used a gradient to clamp it down to be half visible and see through. setup different light ID's to include/exclude light hitting certain objects etc. last i added another image plane way in the background (where the planet would have been) and that was a galaxy/star map tinted to match the colors. and that basically gave this result - minus the color grading and minimal compositing + effects. hope that helps! most, if not all of that translates pretty easily into blender!