Matt Damon’s action-packed film career is highlighted by clashes with various opponents—trained assassins, Nazis, Boston cops, witches, the All Blacks, deadly viruses—but he has never gone up against an entire planet.

In 20th Century Fox’s “The Martian,” Damon is an astronaut inadvertently left for dead on Mars and fighting to survive with little hope of rescue. But his character, Mark Watney, is a determined, resourceful person who decides to “science the sh_t” out of his problem, as the world soon becomes aware that he is still alive.

Not science fiction

Here are five things you should know about “The Martian”:

1) The protagonist is not an action hero. “Actually, astronauts are some of the most fit people,” Damon said. “Everything that happens to them in space, not to get grotesque, but every bowel movement they make gets sent back. They vacuum-pack it and then examine it later to see the effects the journey is having on their bodies. They’re trying to figure out how we can live out beyond our own planet and what are the repercussions of that kind of travel. So it’s really The Best of the Best.”

Watney is also funny and ironic, qualities that make him a relatable, offbeat character—he is largely based on Andy Weir, a neophyte novelist whose 2011 book, “The Martian,” the film is based on. Part of what makes the film work is that it’s based completely on real science, not science fiction. “The Martian” values reality over fantasy, even if it’s set in outer space.

2) The book was a surprise hit. Nobody, not even its author, expected it would be as big as it has become. A tech guy, Weir wrote the novel in his spare time, posting the chapters on his blog in 2009; in 2012, he self-published it as a complete book on Amazon. Weir’s scientist friends were crucial as they essentially nitpicked any inaccurate detail found in the book.

It went on to become a bestseller, eventually picked up by Random House to critical acclaim. It topped the New York Times bestseller list, and the film rights acquired by 20th Century Fox, with “Blade Runner” director Ridley Scott and “The Cabin in the Woods” screenwriter Drew Goddard attached.

3) Scott is as tough as people say. Damon signed on primarily because he wanted to work with the famous filmmaker who proved to be strict but open-minded. “Ridley’s like, if it’s no good, he’d say, ‘That’s terrible!’ As somebody who makes movies and has been doing it for 20 years, I love that because you solve the problems a lot quicker and we fell into a kind of shorthand right away,” Damon said. “You know every single thing you’re shooting is going to be in the movie. So you’re not spinning your wheels and wasting time.”

Aside from “Blade Runner,” Scott directed the 1979 sci-fi horror film “Alien,” and a sequel, 2012’s “Prometheus.” He’s not done with space yet, as his next film, scheduled for 2017, is another sequel, “Prometheus 2.”

4) “The Martian” has a fantastic cast and location. Aside from Damon, it boasts Jessica Chastain, Kate Mara, Michael Peña, Jeff Daniels, Kristen Wiig, Chiwetel Ejiofor, Sean Bean, Sebastian Stan and Donald Glover. Ironically, Damon didn’t get to work much with this great cast as his scenes are mostly shot solo. “I go to see all their movies and yet I didn’t even get to work with them,” Damon said. “It was funny.”

The production shot its Mars scenes in the beautiful, isolated Valley of the Moon (Wadi Rum) in Jordan, the perfect stand-in for the red planet. “I was staggered by how beautiful it was,” Damon said. “There’s nothing like it on Earth.”

5) The film is about our shared humanity. Ultimately it talks about how far we would go, what can be done to help Mark Watney considering his impossible situation. “I think that’s the central tenet of this book, that’s something that’s common in humans across cultures; our instinct is to lend a hand to a stranger who needs help,” Damon said. “That’s what’s beautiful about humanity and ultimately the movie’s a very uplifting story. It’s a survival story. It’s about this guy by himself on this planet, but it’s also about this planet that has seven billion people on it who are working to get him back. It’s about the best in us.”

20th Century Fox’s “The Martian” is now showing in cinemas.