Atlantis
Well Known GateFan
Pretty sure people still confuse space opera with Science Fiction.
Even then, people will say that Space Opera is a 'sub genre' of science fiction.
Space opera is a subgenre of science fiction that often emphasizes romantic, often melodramatic adventure, set mainly or entirely in outer space, usually involving conflict between opponents possessing advanced abilities, weapons, and other technology. The term has no relation to music but is instead a play on the term "soap opera". (Wikipedia: Space Opera)