Brian Truitt

USA TODAY

Thanks to Guardians of the Galaxy, 1970s pop stalwarts Blue Swede, the Raspberries, Redbone and the Runaways are finding themselves at the top of the charts again.

The movie soundtrack Guardians of the Galaxy: Awesome Mix Vol. 1 is No. 1 on both the iTunes and Amazon digital-album lists (and No. 2 in Amazon's overall CD sales) with a crop full of AM standards. Yet the tunes also factor into the narrative of the blockbuster Marvel Studios space opera.

"We may not know the name or the band that sings it, but we know the songs," says director James Gunn, who cherrypicked hits of yesteryear in choosing his soundtrack. "Keeping the attachment to Earth helps to keep the movie grounded throughout the whole thing."

Before she died, the mother of Peter Quill (Chris Pratt) gave him a gift: a Sony Walkman and a mix tape of her favorite songs. So Quill's outer-space adventures have extra resonance with David Bowie's Moonage Daydream and Rupert Holmes' Escape (The Pina Colada Song) playing in the background.

Sixteen Sony Walkmans — all the same old-school model, circa 1979-81 — were rounded up for the film. "It's the kind of Walkman that hipsters in Silver Lake or Brooklyn would pay $4,000 for and pretend like they bought it at a thrift shop," Pratt says. "It's super vintage and really kick-ass."

The soundtrack was the exact emotional anchor they needed to grab a mainstream audience, says producer Kevin Feige. "The very people who would go, 'What? A tree, a raccoon, outer space, what is this?'

"You hear Hooked on a Feeling, and it starts to humanize even the most alien of the characters."