Guardians of the Galaxy is already a surefire hit at the box office, taking in over $325 million worldwide since its debut less than two weeks ago. The Marvel Phase Two adventure has also proven to be a hit on the music charts as well, with the Original Motion Picture Soundtrack, subtitled "Awesome Mix Vol. 1" taking the top spot last week on the Billboard 200 charts.

The soundtrack sold 109,000 copies during the week ending August 10, an 83% increase in sales from its first-week sales of 60,000 units. The 12-track collection, featuring classic songs from the 1960s and 1970s such as "Hooked on a Feeling" by Blue Swede and "I Want You Back" by The Jackson 5, was the second motion picture soundtrack to top the Billboard charts this year, following the highly-successful Frozen album.

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Billboard also notes that Guardians of the Galaxy's #1 album is historic since it is the first soundtrack to hit the top spot that is entirely comprised of previously-released songs. All of the tracks were originally released in the late 1960s and early 1970s, and most of them were hits on the Billboard Hot 100 singles chart. Every track except one, Norman Greenbaum's "Spirit in the Sky", was actually featured in the movie itself.

The songs play an important part in the movie itself, with Star-Lord (Chris Pratt) constantly listening to his "Awesome Mix Vol. 1," which were his mother's favorite songs growing up. The tape, and his antiquated Walkman cassette player, are among the few possessions he held onto from his childhood on Earth.

When we spoke with producer Kevin Feige last month, he revealed that every one of these songs was listed by name in the first draft of writer-director James Gunn's script. Here's what he had to say about the songs in an excerpt from that interview.

"They were written in the script. In the very first draft, the original script, and when I have my red pen and read scripts the way I do, I circled each song, and I thought, 'Maybe this will work, but we'll probably have to go through 10, 20, 30 different songs for every cue to land on one,' because that's usually our experience, you have to turn a lot of things over. Every single song is exactly the same that James laid out in his first draft, which I never would have predicted. They're great. They're brilliant."