[rcooled]

I once asked a friend who was a university astronomer about UFOs. He thought that it was a bit presumptuous to assume that anything unusual seen in the sky must be controlled by an ET intelligence. His said that assumption would indicate that we humans already know and understand every single physical phenomenon that occurs within the observable universe, and anything falling outside that realm could only be a device created on some other world. We are an infinitesimally-small speck in an unimaginably-large cosmos, and despite what we'd like to think, our current knowledge of that cosmos is similarly small.

And why is it that the vast majority of these sightings only seem to occur at night, with the object being illuminated for all to see. Why so few, if any, credible daytime sightings?