What a treasure, I just remembered this was one of my first interaction with a commodore 64. Engineer friend of my father was trying (and succeeding) at triggering my 8yrs old curiosity. I was seriously impressed as he showed me the screen vs the sky. Looking at this with my adult eyes today, I am even more impressed at the render and tech behind that piece of software.
Interesting to see the credits of Sky Travel at the end and having an item "pagetable.com" which is currently a C64 dedicated page. It must be one of the longest running pages on the internet...