So, liquid water was recently discovered on Mars, and Matt Damon is in a new movie about traveling to Mars. Which means that a disturbing number of people think Matt Damon's movie, The Martian, is based on a true story. 

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Just for the record, Matt Damon did not go to Mars and his movie is  NOT, I repeat, not based on a true story. Just don't tell these folks, it's more fun to string them along as long as possible. 

So just to clarify, The Martian is not based on a true story. Now Guardians of the Galaxy and Interstellar - yup, totally true!