why do your bones compress in space causing you to be shorter when you return to earth?

Question: why do your bones compress in space causing you to be shorter when you return to earth?
- Keywords:
  bone,
  compress,
  earth
Asked by bugsie to Jenn on 4 Mar 2016.
- Jenn Wadsworth answered on 4 Mar 2016:
  
  Actually it’s the other way round! Astronauts get a bit taller in space because of the disks of the spinal column: On Earth, the disks are slightly compressed due to gravity. In space, that compression is no longer there causing the disks to expand. The result: the spine lengthens, and the astronaut is taller!

Question: why do your bones compress in space causing you to be shorter when you return to earth?