Cluster of luminescent orbs almost like balloons or grapes, moving around each other in a sort of rotational pattern, while flying a straight course at small plane speed. each orb was glowing and appeared to be changing colour, red blue purple/rose pink, green/blue, yellow. there was no sound. at one point it changed direction briefly by descending then resumed course heading se. hard to guage size accurately with night sky as backdrop because there was no size reference, however it was much larger than a drone and perhaps smaller than a hot air balloon (depending on elevation). it flew a straight course while the orbs moved around each other in their cluster. the orbs appeared to be glowing and translucent or had that quality.