What is the sky?
"The sky is no longer the limit for the Air Force"
So where does the sky end then? Looking from Earth at night I can view galaxies far, far away that are certainly 'in the sky'.
According to the ever truthful 'net it's "the region of the atmosphere and outer space seen from the earth." which basically corroborates my thoughts.
Have they developed a Stargate so they don't have to use the sky any more?