In 1928, six months before the discovery of Pluto, Crashing Suns by Edmond Hamilton appeared in Weird Tales magazine in a two-part serial. We discuss what the elements of space opera are and how to define it.
Links:
Crashing Suns by Edmond Hamilton (Part 1) [Weird Tales, Septemver 1928]:
https://archive.org/details/WeirdTalesV12N02192808sasIfcIbc/page/n3/mode/2up
Crashing Suns by Edmond Hamilton (Part 2) [Weird Tales, Septemver 1928]:
https://archive.org/details/Weird_Tales_v12n03_1928-09/page/n3/mode/1up
Space Opera [Wikipedia]
https://en.wikipedia.org/wiki/Space_opera
