Set in 1957, the film follows young Homer (Gyllenhaal) in the mining town of Coalwood, West Virgina, where almost every man works in the mine. After seeing the Sputnik satellite pass over the town while in orbit, Homer becomes inspired to seek a career in rocketry, and leave the town for a new life. He plans to showcase his homemade rockets at the local science fair, though the townsfolk believe he has no chance of succeeding.
Despite this, Homer teams up with the school geek and fellow rocket enthusiast Quentin (Chris Owen), and recruits four of his friends into helping him. Though they fail at their first few attempts, they make several successful launches after experimenting with the fuel and rocket design. However, they run into problems with the law when it is believed that one of their rockets landed astray and caused a nearby forest fire, causing them to be disqualified from the science fair. As if this weren't bad enough, Homer's father John (Cooper) is injured in a mining accident, and now Homer must leave school and take up the work in order to support the family, leaving him with no time to help prove that the forest fire was not their fault. However, the boys' science teacher (Dern) has a firm belief in what they're doing, and gives Homer a book on rocket science, from which Homer teaches himself how to calculate a rocket's trajectory, allowing him to find their own rocket and prove the group's innocence.
They enter their rockets in the local science fair and win first place, allowing them to move on to national science fair in Indianapolis. Only Homer leaves, because of the school's limited funding. Their display wins there as well with flying colors, as Homer receives countless scholarship offers before returning to Coalwood as a hero.
This movie provides examples of:
- Adaptational Attractiveness: Let's just say that most teenage boys don't look like Jake Gyllenhaal, and the real Homer Hickam was no exception.
- Adaptational Ugliness: In contrast to Sonny, the real life Quentin was, though unquestionably nerdy and an Insufferable Genius, mentioned in the book to be "not bad looking" and is shown to be arguably pretty cute. His film incarnation is made out to look much more awkward, with Nerd Glasses and less style.
- Adaptational Villainy: Homer's father. He was a lot less of a Jerkass in the book, and more supportive of Homer's rocketry work. He even helped Homer with some of the advanced math that gets credited to Quentin in the movie. (Turns out managing a mine requires intelligence and knowledge of engineering. Who'da thunk it?)
- The union members could fit as well. In the movie they were depicted as violent, when they were depicted at all. In the book, while they may have hated Homer's father, they had no anger towards Homer. Some even helped him make rocket components. One even suggested telling John L. Lewis, the head of the UMW- and renaming them "The United Mine and rocket Workers of America".
- Adaptation Dye-Job: As shown in the epilogue, the real-life Miss Riley had black hair. She's a blonde in the movie.
- All Girls Want Bad Boys: Referenced: After the boys are arrested for allegedly causing the forest fire, Quentin complains that "Now we're practically ex-cons" and that girls will never want to dance with them. He is told that he doesn't know about girls.
- Arc Words: "It's not gonna fly unless somebody [does thing]" The boys initially have to light a fuse and run away, but the film shows their progress by advancing to pulling a string to light a match by pulley, to pulling an electric switch, to pushing a button.
- Artistic License Engineering: One of the machinists at the mine suggests using SAE 1020 steel for the rocket nozzles, saying that it will 'take the heat', and that it's expensive. SAE 1020 is a common medium-carbon steel without any special properties; Nickel-Chromium stainless steel would be a far better choice, as it loses much less strength at high temperatures.
- Calling the Old Man Out: Homer's frustration with his dad pressuring him into following in his line of work culminates in an argument over how everyone except his dad realizes that the coal mine is done for, with Homer declaring that if he wins the science fair in Indianapolis and goes to college, he's never coming back to Coalwood.
- The Cameo: Photographer O. Winston Link, famed for his documenting the final years of steam locomotives on the Norfolk & Western (featured in the film) appears as the locomotive engineer who waves at the boys.
- Catch-Phrase: Quentin, the team bookworm, often uses the phrase "Prodigious!" when something good happens for the team. Roy attempts this at one point, but butchers it into "Predigenous!"
- Company Town: Coalwood.
- Composite Character: October Sky merged Sherman Siers and Jimmy O'Dell into one character called Sherman O'Dell, while the book kept them separate.
- Dogged Nice Guy: Homer is this to Dorothy Plunk, who ends up dating his brother.
- Dying Town: Coalwood.
- Eating Lunch Alone: Quentin does this, usually while reading. Homer walks up and asks about how to construct a rocket, but Quentin doesn't take it seriously until Homer actually sits down. Incidentally, the entire cafeteria takes close note of this development.
- Exact Words: After the second attempted launch lands at the mine (which wasn't empty at the time), Homer's dad forbids Homer from any more rockets "on company property." Homer waits until after he and his friends are alone to highlight the last part, and he's not discouraged when they protest that the company owns all the land for miles around.
- Failure Montage: There's a long sequence of rockets exploding on the launchpad before the boys are shown figuring out what the problem is.
- Fantasy-Forbidding Father: Homer's dad at first.
- The Film of the Book: The story is based on Homer Hickham's memoir, Rocket Boys
- Gangland Drive-By: During a dispute between the mine and the miner's union, someone fires a shot at John while he's in the kitchen, followed by the sound of tires squealing as the shooter drives off.
- The One Who Made It Out: Homer Hickam especially, but all of the Rocket Boys qualify.
- I Like Those Odds: O'Dell.
- Ill Girl: The kind and encouraging schoolteacher, Miss Riley, who is revealed to suffer from Hodgkin's Disease during the third act of the film, giving the Rocket Boys that extra emotional push to pull off their last, climactic, rocket launch.
- Jerk with a Heart of Gold: Homer Sr.
- Papa Wolf: Homer Sr. subverts this trope by being the Papa Wolf to someone else's son when he sees Roy Lee being beaten by his stepfather.
- Poor Communication Leads To Wrongful Arrests: Nobody shows the boys the rocket that caused the forest fire until after Homer uses the math book to find where their rocket landed, proving it wasn't their fault.
- Pursue the Dream Job: Homer takes a job in the town's coal mine after it seems his hobby of rocketry has caused a forest fire. He does well there but when he figures out the fire started too far away for a rocket to have started it, he begins pursuing rocketry again, determined to get out of that town and go to college. He eventually goes to work for NASA.
- Railroad Tracks of Doom: Subverted: The boys rip up the tracks of a supposedly-abandoned spur line to sell the iron for scrap. One of the boys lampshades this trope, asking if the the tracks really are unused. Sure enough, the moment they've got the heavy rail fully out of alignment, they hear a whistle... Frantically, they try to get the rail back in place, seemingly to no avail as the locomotive bears down on them... Then at the last moment, the train turns away down the main line; and the camera pulls back to reveal that the line they tore up was inactive.
- Reasonable Authority Figure: The principal. He doesn't tolerate any nonsense from the Rocket Boys, but when the evidence suggests that they didn't start the fire, he gets the police to review the case, and he's the one who recognizes what really happened—the "rocket" that started it was a flare from the nearby airport—and as soon as he realizes this, he actively works to help the Rocket Boys pursue their goal of winning the science fair.
- Recognition Failure: One of the first people to congratulate Homer for winning the national science fair is his hero, Wernher von Braun. Homer doesn't recognize him.
- Tragic Keepsake: Homer carries with him Ike Pekoski's identification disk.
- "Well Done, Son!" Guy: Homer's mother calls out her husband on the fact that he doesn't miss a single football game featuring Homer's older brother, but he hasn't been to a single one of Homer's rocket launches. Homer sets the record straight near the end of the movie:Homer: Dad, Dr. von Braun is a great scientist. But he isn't my hero.
- "Where Are They Now?" Epilogue: All of them ended college.