What makes space so cold ?Will the sky completely go black because the universe and our planet keep expanding ?

Question: What makes space so cold ? Will the sky completely go black because the universe and our planet keep expanding ?
- Keywords:
  black,
  cold,
  expand,
  sky,
  universe
Asked by bluemarshmellos to RocketRich, Jenn, Floris, Elie, Col Op on 16 Mar 2016. This question was also asked by Octotiger🐙🐯, T, T'keyah Mendes.
- Floris Van Den Berg answered on 16 Mar 2016:
  
  Temperature depend on a lot of things, but mainly 2 things, a heat source (the sun) and the ability to keep the heat. In space you see huge changes in temperature, if something is in direct line of the sun it get really hot, and when its in the shodow its really cold. Ther eis not much mass to keep the heat, so often quite cold.
  
  I dont think the sky will go black , even with expansion there will be nearby suns I guess.

Question: What makes space so cold ? Will the sky completely go black because the universe and our planet keep expanding ?