why do we have planets in space?

Question: why do we have planets in space?
- Keywords:
  planet,
  space
Asked by bongybing to Andy, Duane, Giovanna, Katie, Theresia on 15 Nov 2014.
- Duane Mellor answered on 15 Nov 2014:
  
  I think it is effect of gravity causing rock, dust and gases to collect around the sun as things started to orbit the developing sun.

Question: why do we have planets in space?