Aficionados — what we now affectionately call geeks — who packed all three Welles auditoriums, watched movies, ate popcorn, drank lots of coffee, smoked pot in the bathrooms, yelled at the screens, chatted, and got to know each other between films.

On a cold winter weekend in February 1976, a tradition was born in Cambridge. When the projector at the Orson Welles Cinema rolled at noon, and “This Island Earth” flickered across the screen in Cinema 1, a jolt shot through the local science fiction community. It was the beginning of the first, and later annual, 24-Hour Science Fiction Movie Marathon. Among the other 13 films playing between noon and noon were “The Day the Earth Stood Still, “Them!” “Fantastic Voyage,” and “The Incredible Shrinking Man.”


On Feb. 15, the 40th annual Marathon, simply called SF40, takes place at the Somerville Theatre, which has been the event’s home since SF32, in 2007. The lineup includes three films from the first one — “This Island Earth,” “The Day the Earth Stood Still,” and “Them!” — along with last year’s hits “Edge of Tomorrow” and “Snowpiercer,” the classic “2001: A Space Odyssey,” the terrific family film “The Iron Giant,” the goofy action-fantasy “Big Trouble in Little China,” and many more.

Acton resident Simon Volpini and Peabody resident Brian Yelverton share the honor of being the only two people who have been to all 39 previous Marathons. Ready for the big 4-0, they both remember finding out about the first one.

“I was a junior at MassArt at the time, and I saw an ad for it in the Phoenix,” said Volpini. “I loved movies, and the idea of watching for 24 hours intrigued me. There was also an offer that if you watched at least 10 of the movies you got a free champagne breakfast. But that part was kind of anticlimactic, because you were so blown away by then.”


Yelverton recalls seeing the ad in the Cambridge alternatively weekly The Real Paper.

“I was into checking out obscure movies,” he said. “Finding out about this was great because this was before videotape, so there was no way to see half of these films. I’d seen bits and pieces of them on television; but there were a lot that I’d never seen before, and seeing them on the big screen was going to be a big treat.”

The movies were and obviously still are the big attraction. But as anyone who has attended before will attest, the Marathon is not just about the movies. It’s a people thing, a quirky village, rising “Brigadoon”-like, once a year. Audience members bring ray guns and coolers of food, take part in trivia contests or vie for a prize by making the best tinfoil hat, and meet up with friends in the dark whom they haven’t seen since the previous Marathon.

Video editor and former Cambridge resident Caleb Oglesby, who attended SF1 when he was 11, moved to Manhattan a couple of decades ago, but he still shows up at the Marathon every year, having missed only two.

“I was already staying up late to watch horror and science fiction movies on television.” he said. “My older sister was going with a bunch of her friends, and I wanted to go; so she had to take me. I made it through that first one and it was great. These were movies I had read about and seen pictures from in ‘Famous Monsters,’ and this was the first time I got to see so many of them. It was a genre I loved, and this was a chance to be immersed in it surrounded by people who felt the same way.


“There’s also that sense of friendship and community,” he added. “There are people I’ve known since fourth grade who I still see every year at the Marathon, and that’s the only time we see each other.”

Somerville resident and picture framer Meta Luna (real name Jennifer Pozark; her Marathon handle is the setting of “Forbidden Planet”) has been going every year since SF4, when she was 8. She also tagged along with an older sister.

“It’s about movies, but it’s also about camaraderie and junk food and sleep deprivation,” said Luna, who always brings snacks, a pillow, and her stuffed Marvin the Martian. “Over the years, of course, you get to know people and you get all the in jokes. A lot of it is the traditions, but it’s still fun to watch the movies, to be half asleep, and to be with all these people who are kind of crazy the same way that you are. It’s definitely become more than just movies; it’s the whole experience.”

The Marathon’s producer, Garen Daly, first experienced the science fiction exercise in excess when he became the manager of the Orson Welles, in 1978, the year of SF3. A longtime science fiction fan, he took over running the Marathon in 1987. He realized, from the start, that the Marathoners were hip, that they got what was going on, that it was OK to show both classics and bad B movies.


“It’s a very smart audience, an audience that knows the language of film fluently, and they appreciate the intelligence and the schlockiness of film in all its glory,” said Daly. “That makes it interesting because when you have people who admire the intelligence of films but also love the silliness of films, you know they have a sense of humor. Knowing that when you’re programming an event like this means that you can push the boundaries of what you can show and what you can’t show.”

All of the Marathoners interviewed admitted that they never make it all the way through without napping, either by design when there’s a film they’ve seen too many times, or by nodding off due to exhaustion. And their post-Marathon experiences are similar.

Volpini: “Sometimes I think the circadian rhythm is thrown so far off that I start thinking, ‘I should be tired. Why am I not sleepy?’ So I’ll watch something on TV and fall asleep.”

Yelverton: “I just try to get home, and usually decide I’m not that tired, but I take a quick nap, then try to get back on a regular sleep schedule.”

Oglesby: “I sleep all the way home on the train [to New York]. But when I get home I decompress by sitting down with my family and watching another movie.”


Meta Luna: “I go out and have some lunch with friends. But when I get home there’s definitely some sleep involved before too long.”

BOSTON SCI-FI FILM FESTIVAL

The nine-day series of new features and shorts is at the Somerville Theatre starting Friday, culminating in the 40th annual Boston Sci-Fi Movie Marathon, running from noon on Feb. 15 to noon on Feb. 16. Go to www.boston

scifi.com.