At its simplest, space opera could be thought of as science fiction that's heavy on the adventure and light on the actual science. Space opera, at least originally, was defined by what it's not—hard science fiction. Although the term was initially meant as a disparaging label, fans and creators have embraced it in the decades since it first came into use.

Although it's not the only type of soft science fiction, space opera definitely falls toward that side of the spectrum. There's no reason you can't incorporate some scientific rigor into your space opera setting, despite the term's origins. For it to truly feel like space opera, though, the focus should be on your characters and the adventure, not the science behind your setting's advanced technologies.