Exiting my greenhouse on june 10, 2017 in delaware county, indiana at ~10:18 pm and noticed yellow lights in the west sky above the sunset lit horizon. my first impression was a firework explosion as the lights were up to 100, but there was no sound and they stayed in the air in a swirling motion and maintained their elevation. they drifted with the south to southwest wind. the objects were ~1/2 mile away and at about 40 degree elevation. their size would be like those of fireworks lights. i went inside my home to get my digital camera and could not see them illuminated on the display screen, so no photo was taken. they drifted to the northwest until out of my sight. my thought is that maybe the lights were a "swarm of drones" like i saw on "60 minutes" used by the military. their speed was likely equal to the wind speed.