It's interesting to look at the way cinema, our most popular artform, has portrayed extraterrestrials over the years, reflecting fears – and hopes – in the world at large.

After all, any detailed discussion of intelligent non-human life-forms, apart from the scientific question of whether they can exist, has always been restricted to fiction and film.

In the 1950s, fears over the A-bomb and the implications of the Cold War, gave us movies such as The Thing from Another World, Invasion of the Body Snatchers, It, the Terror from Beyond Space, and the first film version of War of the Worlds, where alien visitors were far from friendly.

With the advent of transcendent New Age wishful-thinking in the Sixties, 2001: A Space Odyssey began the mystical and inspirational strand of movies leading to the spiritual crux of Close Encounters and the hallucinatory fantasy of Star Wars in the Seventies, to ET in 1982 and eventually Contact a decade later.

Enemy Mine (1985) was a landmark of the spiritual approach with a man and an alien marooned on an inhospitable planet during an intergalactic war. They have to make a tentative peace and finally become firm friends, the man benefiting greatly from the alien's spirituality. Alien Nation (1988) also depicted humans learning about spirituality from non-humans.

But running parallel and overtaking these optimistic treatments were the films returning to the theme of hostile invaders, probably allegorising perceived growing military or political threats on Earth.

Thus we had the Alien and Predator series, Independence Day , and Signs – although all of these suggested that gung-ho humans could win the day.

Such movies underline the irony that, to many people on our planet, spirituality has become much more alien than any possibility of intelligent space beings.

If we ever do have a "close encounter of the third kind", we may just discover a new kind of spirituality, and find ourselves able to invest in the unknown, the alien, instead of avoiding it.