i had been watching these things for two nights prior to this.just as it was getting dark three appeared.i went inside to get my wife to come and see,when we returned outside (about 2 minutes later) the sky was full of them, more than i could count.they were sitting still with red,blue,green,and white lights occasionaly blinking.we noticed to the west there were three significant ones in a triangle pattern,one at top two on bottom.the one on the lower left was really going crazy with blinking its lights.it appeared to be signaling the others.occasionaly some would move around.after watching for a while we got creeped out and went inside.shortly after this noise i had been hearing for several nights prior to this started up.it is a fluctuating humming sound like that of construction equipment running that goes on all night.by daylight everything was quite and no crafts in sight.