Do planets ever get smaller?

Question: Do planets ever get smaller?
- Keywords:
  planet,
  size,
  space
Asked by blue13 to Hayley, Jason, Sophie on 21 Mar 2013.
- Hayley Evers-King answered on 21 Mar 2013:
  
  I don’t think so. Unless they get hit by a lot of asteroids and bits break off, then maybe they could get smaller.

Question: Do planets ever get smaller?