Unidentified flying objects (UFOs) are reported annually.
Most of them can be explained by natural phenomena such as bright stars, meteors, aurora, and rare clouds, or artificial objects such as satellites and airplanes.
Even after removing the cause, there are cases where it cannot be explained.
Without much research, dismissing the possibility that a UFO is a sign of a visitor from outside the earth is as much as accepting that idea without considering a more general interpretation.
It will be unscientific.