Space Opera is a subset of science fiction that usually includes star travel and sweeping stories. I've been reading stories from this genre since the 1960's. Before that I was reading horse stories, Enid Blyton, or Dick and Jane.
io9 is "a daily publication that covers science, science fiction, and the future". There are articles, discussion forums, blogs, etc. found there that are wonderful. I have read many of their articles.
The one I read today is a must read for those of us who like space opera.
Major Highlights in the History of Space Opera
I expected to see H.G. Wells on this list, but he's only referred to in passing. Then I realized that while he wrote science fiction, he may not have written space opera. This article goes back to 1901 and a novel titled A Honeymoon in Space by George Griffith.
Read the article. It's fascinating. If you like science fiction, you may want to follow io9.