A Space Opera is usually set in outer space or on a distant planet. In most cases, to keep the story fast moving, a spaceship can fly almost unlimited distances in a short time, and can turn on a dime, without the boring necessity of decelerating. The planets usually have Earth-like atmospheres (Earth’s moon is an exception) and exotic life forms. Aliens usually speak English, sometimes with an accent. The machinery of space opera often includes (in addition to spaceships) ray-guns, robots, and flying cars.

Space Opera backgrounds may vary considerably in scientific plausibility. Most space operas conveniently violate the known laws of physics by positing some form of faster-than-light travel. Many space operas diverge even more from known physical reality, and not uncommonly invoke paranormal forces, or vast powers capable of destroying whole planets, stars, or galaxies.