The biggest achievement Steven Spielberg made with this film was that it was the first movie to treat a subject that had previously been dealt with using campy effects and rubber suits with dead seriousness.

The goings-on in Roy and Jillian's lives are trivial - the mundane details of running a family and household are held in proper perspective when suddenly they're faced with the enormity of what's occurring around them. It has an almost documentary feel that is still the benchmark for movie realism. Just watch and listen to the dialogue during the air traffic controller sequence as the film opens.

Spielberg also showed (more so than he did in Jaws - albeit accidentally - by not showing too much too soon only served to heighten the anticipation and sense of wonder we all felt. For millennia we've looked at the stars and wondered, and he captured that in just a few iconic scenes.

The camera staying stubbornly on Roy's Ford F150 as the piercing light stabs at it and causes a miniature whirlwind inside is a standout example. So is Jillian and Roy standing in the middle of the road as they tend to Barry when the first of the three craft drift in near silence overhead.

And of course, after showing glimpses of ruby lights emerging from behind the rocks, the first wide shot of the mother ship appearing behind Devil's Tower raises hairs on your arms as effectively as the first appearance of the Tyrannosaur in Jurassic Park ever did - proof that's the image, not the effects, that matter.

Strange happenings have been occurring across the world, and they're making an impact on cartographer Laughlin (Balaban), astrobiologist Lacombe (Truffaut) and suburban blue collar electrician Neary (Dreyfuss). Like a woman he meets (Dillon) Neary has been getting visions of a strange geological shape, and after the movie spends a great deal of time building on the amazing happenings around the world from Mongolia to the US and India, Roy and Jillian find themselves drawn to a desolate mesa in the middle of the Wyoming desert to witness the unimaginable.

If you need a reason why Steven Spielberg is the most spectacular filmmaker we have, look no further.