A space engineering professor said aliens should be the "absolute last thing" one would consider regarding the unidentified flying objects the US military spotted and shot down over the past week.
When asked during a Pentagon briefing, defence officials didn't rule out the possibility that the origin of the so far unexplained objects is extraterrestrial.
An "unidentified object" shot down by a US fighter jet over Lake Huron on Sunday was the fourth encounter in eight days and the latest military strike in the extraordinary chain of events over US airspace.
