The Hollywood heavyweight, who was behind the Alien films franchise featuring deadly killer extraterrestrials, is not expecting a meeting of minds if an intelligent species does descend upon the Earth.
In an interview with Sky News, the movie legend said they may well not “come in peace”.
He said: “An expert I was talking to at NASA said to me, ‘Have you ever looked in the sky at night? You mean to tell me we are it?’ That’s ridiculous.”
He is convinced there could be 100 to 200 different species out there somewhere in the Universe.
But, unlike many alien believers, who are certain that aliens are already on Earth, secretly working with world leaders, he thinks it would be more of a ‘War of the Worlds’ style affair if it happened.
He said: “When you see a big thing in the sky, run for it. Because they are a lot smarter than we are, and if you are stupid enough to challenge them you will be taken out in three seconds.”
Scott spoke ahead of the release of his new film Alien: Covenant, which comes out this month.
It is the story of the crew of the colony ship Covenant, which finds a planet on the far side of the galaxy, which is felt could be a new paradise, but houses a deadly threat.