I do believe there are likely to be other intelligent life forms in the universe, but fail to see why they would bother with us.  Unexplained phenomena could be all manner of things.  I have somewhere a photo with a strange thing in the sky, but I suspect a speck of dust in the camera.   My son and some of his friends claimed to have seen a UFO some time ago. However, they had been in the pub for a couple of hours and another explanation suggests itself.