is the earth a massive horizon, so it keeps going and going and going on a flat (and/or hilly) surface forever until

Question: is the earth a massive horizon, so it keeps going and going and going on a flat (and/or hilly) surface forever until you get to the end country? (its confusing me a lot! )
- Keywords:
  earth,
  horizon,
  surface
Asked by 10kempstera to Mike, Pip, Tianfu, Tim, Tom on 26 Jun 2012.
- Tom Lister answered on 26 Jun 2012:
  
  wherever you stand, there will be a horizon as the earth curves downwards in all directions.
- Tim Stephens answered on 26 Jun 2012:
  
  The earth is a giant ball. Wherever you stand, there will be a horizon. If you kept going in exactly the same direction, eventually you’d get back to the same place.

Question: is the earth a massive horizon, so it keeps going and going and going on a flat (and/or hilly) surface forever until you get to the end country? (its confusing me a lot! )