Driving along South River Rd. and saw three big white lights in triangle formation above the Wabash River

I was a passenger in a car that my daughter was driving and heading from Granville Bridge to West Lafayette along the Wabash River when I looked out the window and saw above the tree line of the River three large white lights in triangular formation about 200 feet up and about 200 feet apart from each other and they weren't moving. I kept looking up as we drove past and the lights just stayed in place...hovering...as they were visible between the tree limbs that didn't have leaves on. We didn't stop. My daughter couldn't see the lights from her seat as she was driving and couldn't see through the car roof. I know this area very well and there aren't any tall buildings built in this flood plane near where Wea Creek drains into the Wabash. It wasn't an aircraft coming into land at the Purdue University Airport...as this is an EXIT ramp where small craft take off and fly above the river...as I've viewed them while kayaking in the river a couple years prior and their engine noise really messes up shooting a video. This triangle of lights never broke formation. No other lights on the craft were visible, nor did the lights change color nor change from their round shape which I estimated to be about 6 feet in diameter. No engine sounds were detected above the sound of our own car engine / wind noise. I didn't see the outline of the craft as it was dark out. No one flies drones in this area nor could a drone carry lights that big. I was too amazed by the sighting to grab my camera and take some pics or video. I'd never seen anything like this before and didn't know the history of whether this was alien or something our own special ops programs built. I didn't know if theses type of craft ever caused mischief like abducting people...so, we didn't stop to see what it was up to. I suspect it was monitoring the activity of the airport.