UFO Seen Hovering Near Plane in Chicago

There are sightings all the time but this most recent event has skeptics thinking there might be aliens.

This video taken in July but only uploaded to YouTube yesterday shows a three lights outside of an airplane.

The lights just sit there for a while outside of the window but then seemingly start to fly out of view pretty quickly.

One YouTube comment said "Those are ducks. Ducks take on a spherical shape, and glow brightly when flying at high altitudes." That's not right, right? I've never heard anything like that before.

What do you think? Is that a UFO? Something else?