What is the black space that we see at night, made up of? (just the black stuff!)

Question: What is the black space that we see at night, made up of? (just the black stuff!)
- Keywords:
  black,
  colour,
  space
Asked by wizzyg12 to Kate, Claire on 24 Jun 2013.
- Kate Husband answered on 24 Jun 2013:
  
  The black stuff is where we can’t see a galaxy or a star so it’s genuinely empty space. That said there will be some faint radiation coming from that patch of sky, some of it will be microwaves left over from close to the Big Bang and some will be at other wavelengths from stars and galaxies that our too faint for us to see. So in fact the sky isn’t black – it’s just a very very very dark grey!
- Claire Lee answered on 24 Jun 2013:
  
  Yup, it’s nothing – pure, empty, nothing.
  
  There is a wonderful photo by the Hubble telescope called Hubble Ultra Deep Field.
  
  That photo covers the space in the sky that is smaller than what a 1mm x 1mm square of paper would look like if you held it at arms length.
  
  And yet – I think there is only 1 single star in that picture – everything else you see is an entire galaxy, trillions of miles away. The black stuff in between? More empty space.
  
  Space is huge, and full of emptiness

Question: What is the black space that we see at night, made up of? (just the black stuff!)