WIKIPEDIA DEFINES HORIZON AS FOLLOWS:
The horizon is the apparent LINE that separates earth from sky.
More precisely, it is the LINE that divides all of the directions one can possibly look into two categories: those which intersect the Earth’s surface, and those which do not.
The Bush/Cheney White House likes to throw around navigational terms like “Stay the Course” and “Horizon” .
As someone who has earned a living as a navigator, I submit that the Bush/Cheney Stay the Course policy in Iraq violated basically all the principles of navigation and now even the simple concept of horizon has them flumoxed.