On Oct. 8, fans in New York City will line up to watch Ad Astra.

Only instead of Brad Pitt in a space caper, they’ll get four guys from the tri-state area playing noodly prog-rock/fusion jams.

What happens when the seemingly obscure name of your band suddenly shares a title with a big mainstream Hollywood movie?

The members of Ad Astra are finding out.

“We have been getting asked and teased about this since April when the movie was first announced,” Ad Astra guitarist Joe Nardulli tells The Post. “We’ve been having fun saying Brad Pitt contacted us and he’s doing a documentary about the band.”

Just scroll through the band’s Facebook page for some choice or confused comments.

“I thought Brad Pitt joined the band,” one person writes. “Joe did you get any royalties from the ‘Ad Astra’ movie coming out?” another posts.

One fan wearing one of the band’s T-shirts was recently stopped and asked what it had to do with the film.

But it’s all good for the quartet of New Yorkers that started back in 2004. They’re just excited that people may now know how to pronounce their “weird, esoteric” name, which is Latin for “to the stars.”

Nardulli calls himself a music “hobbyist,” explaining that “it would be great to do music for a living, but the music we love . . . is not in high enough demand to afford us to do so.” Now 53, he recorded an album of his own songs and later formed a group to play them. But Nardulli didn’t want to name the group after himself, so the band took its moniker from the title of one of its songs, which also happens to be Kansas’ state motto.

Besides the potential for piggybacked publicity, the band is simply excited to see the film.

“I saw the trailer and it looks great,” says Nardulli, who works as an engineer. “When they faded in the title, I actually got goosebumps. It was as if I was seeing the name of my band.”

The band, which also includes keyboard player Eric Davis, bassist Harold Skeete and drummer Tony Savasta, now cracks jokes about Pitt onstage (and will again when they play Harlem’s Shrine World Music Venue on Oct. 8). And the guitarist says there’s one other potential bonus.

“If the movie has got a good theme song, maybe we’ll cover it.”