As everyone knows by now, I've always got the little Sci-Fi theatre on in the background as I work or forum. Ah, the joys of being semi-retired. Watching The Chronicles of Riddick right now. The title contains the word chronicles, which brings the film to an immediate 50 out of a possible 100 points, but that's not what I'm on about in this thread. A portion of the film takes place in the Igneo System (groan...) on planet Crematoria (kill me now!) and it's this planet that is the final straw in a film I love to hate. A planet is presented to the watcher that is so close to its sun that the sunrise causes a dramatic, explosive, pyrotechnic reaction across the landscape. Yet, the planet has a breathable atmosphere. Why? Why in the universe would this place have an atmosphere at all, let alone one breathable to humans? This planet is impossible. And there are many impossible planets in Science Fiction. In Robert Silverberg's Majipoor series, the planet of Majipoor is described as being rather larger than Earth, but with less gravity because somehow it is "fluffy" inside. Sorry, no. Have you written, or are you writing, an impossible planet? Does it matter to you that it be impossible? Is this overlookable to you or no? Discuss.