Well the other users on this page are trying to apply science to the fiction.  But since the writers write what they feel like writing, without consulting a university staff of astronomers and astrophysicists, they come up with immense errors.  Star Trek is about the stories, this fiction, and the science would be secondary.  Don't take my word for it though ask the people who wrote it.  The next generation technical manual clearly states the writer's position on it in the forward.