1) Galaxy Magazine was one of the great science fiction mags of all time. Its stories, and its storied editor, H.L. Gold, helped to define short-form sf for generations.
2) The novelette or novella length is one of the great, underappreciated forms of writing. It's longer than a short story, so the writer has a bigger canvas. But it's more focused than the novel, offering the writer both a special challenge and a unique opportunity.
What they have in common is that e-publisher Rosetta Books is running a sf novella contest as part of "The Galaxy Project." The prize money is real, and so is the prestige. If you are interested in writing novella-length sf, you can find the details here.