Whilst this tutorial creates the imkage of the horizon moving away and above you, it is also a technique that can be used for a backdrop insde a space station for example, where the floor is at 90 degrees to the horizontal due to centrifugal force.
The technique was also used by Arthur C Clarke (the writer of 2001: A Space Odyssey) in his RAMA series which if you have not read it, is well worth the read.
There have been rumours for years that this was to be made into a movie and financed by (and directed by and starring) Morgan Freeman.
Still waiting though.
