[delichon]

That's when it collides with the skybox, like the sailboat at the end of The Truman Show.

[dmd]

Or like Apollo 8 in the incredibly funny book Unsong.

[agg23]

Unsong is extremely amusing to me for some reason. Something about how Scott comes up with reasonably sounding similarities and manages to make those relate to an overall story.

[b112]

David Brin thinks so:

https://en.wikipedia.org/wiki/The_Crystal_Spheres