Well thats because it's really an ancient spaceship. Star wars already happened, that's how we have the movie. If you're wondering how that happened, they basically hired one of the underground hollow earth reptilian aliens to go back in time to film it and hold on to it til the year 1977. The alien is immortal, so they told him to meet us at the same spot they dropped him off with the film and thus star wars was put on the big screen. Theyve sent him back multiple times to get better quality