Very legible, love the open space with the sky and stars. One suggestion is to maybe move the text in a tiny bit as it looks a little bit close to the edge, although I think full screen it would probably be fine.
These are also very legible, I would move the text a little bit up on the second one as the postcard is very image and text heavy on the lower half.
It would be nice to see variation in the typefaces. I like how the text placement is different on all of them too. I also think the overall layout of all three is very similar but the imagery being all very different helps.