I voted Thursday 8pm because it sounds mysterious. It also gives the impression something radical happened on that time, which is especially nice if your story deals with adventure or mystery or drama. Tho, it could work with comedy too, and would be a nice twist.
The summer one sounds like some romance story, as Kelheor said.
As for the first one, it locks the first impressions on the story around sci-fi and space stories. It might be a bit too narrow? It depends on what you want to do with your title, or what your story deals with.