how do we kno so much about space and exsactly how far each planet is away without being sent there in a shuttle?

Question: how do we kno so much about space and exsactly how far each planet is away without being sent there in a shuttle?
- Keywords:
  space
Asked by harln002 to Ben on 16 Nov 2011.
- Ben Still answered on 16 Nov 2011:
  
  We can watch the motion of the planets in the night sky and from the patterns they make you can calculate their distance from the Earth and the Sun. Once we have a distance we can calculate the size of a planet from its size in the night sky.

Question: how do we kno so much about space and exsactly how far each planet is away without being sent there in a shuttle?