Why? The three 'S'-es. Superman (Richard Donner, 1978), Spielberg and Star Wars (George Lucas, 1977). That film, of course, became a massive commercial hit - the biggest ever box office at the time - and proved a market appetite for science-fiction with sophisticated special effects. Straight away, every studio was looking for its own Star Wars, and pop culture was once again obsessed with science fiction.

While the genre had been present since the dawn of cinema, it reached a watershed in 1968 with the release of two landmark films, Planet of the Apes (Franklin J. Schaffner) and 2001: A Space Odyssey (Stanley Kubrick). 2001 was perhaps the first Science-Fiction blockbuster as we know it, with extended sequences showcasing mind-bending special effects. Though that film became the biggest-grossing film of the year at the domestic box office and won awards including the Academy Award for Best Special Effects, MGM and other studios were concerned by other business issues - the film was completed 16 months over schedule and the $6m budget was overspent by $4.5m. Those Oscar-winning effects didn't come cheap, with 205 special effects shots taking nearly 2 years to complete. At the time, no-one could compete with 2001 at a reasonable budget and schedule.

In the following years, big budgets were still spent on the genre in order to cash in on the new craze, but with more achievable scope. Though Universal spent $6.5m on The Andromeda Strain (Robert Wise, 1971), the film has no big effects sequences, largely being a psychological film. It earned the studio around $8.2m domestic. A profit, but a modest one. Independent films such as The Omega Man (Boris Sagal, 1971) and Soylent Green (Richard Fleischer, 1973) found mixed success but attracted big names and major distributors, while the studios got some returns from releases such as Logan's Run (Michael Anderson, 1976). It was clear by the middle of the decade, however, that the big wave of science fiction off the back of 1968 wasn't happening.

The most important film in the genre since 2001, however, was Star Wars. Wary of the genre, and conscious that the more critically praised or commercially successful science fiction of the decade so far featured philosophical exploration of complex concepts such as Silent Running (Douglas Trumbull, 1972) and Logan's Run, United Artists passed on the film. Universal and Walt Disney too. 20th Century Fox didn't care for the idea, but liked Lucas so jumped on the film. They got nervous as the budget was exceeded, and there was much speculation in the industry about what the film would do to Lucas' career and the Studio's finances and leadership.

On its release, it was an instant phenomenon, of the sort never seen before. There had been kids movies, and science fiction movies, and even some kids movies that were science fiction, such as Escape to Witch Mountain (John Hough, 1975). But these were cheap films. Star Wars was a kid's science fiction film with a sizeable budget using very cutting edge techniques that, as with 2001, gave the audience something they had never seen before. The iconography, the score, the story and characters shot to prominence in pop culture in a way that few other things had, and certainly not out of nowhere like this did. The word was out: Spaceships were big business.

Keen to cash in on the action, every studio was searching for new (or old) projects that could be hitched to the bandwaggon. 20th Century Fox itself had a spaceship script it had been developing unenthusiastically via a producer's production company. Now, of course, it had to happen. They rapidly greenlit Alien (Ridley Scott, 1979).

Luckily for some, there were studios already doing spacey films anyway, and Star Wars had just kicked the door in. The first to benefit was Close Encounters of the Third Kind (Steven Spielberg, 1977) which had a troubled production. Initially estimated at $2.7m, the film had now cost Columbia $19.4m, with effects alone reaching $2.4m, the budget for another normal film. The film had also gone over schedule, which was probably fortunate as it would no longer be competing with Star Wars. On release in November and stoked by Star Wars, it grossed $116m domestic, Columbia's best box-office yet.

The third massive success that set the agenda for the following decade was Superman (Donner, 1979). An international co-production and the biggest budget for any film to that date, it earned the producers $80m domestic on a budget of $55m. Its worldwide gross of $300m made it the No.2 film of the year and cemented science-fiction's place. This wasn't another flash in the pan like 1968. The public remained hungry for more.

This all came at the right time. Film budgets were beginning to rise, as were the quality and sophistication of special effects techniques.