All galaxies outside of our own are moving away from us. The galaxies that are furthest away are moving the fastest. They are not moving through space, they are moving in space due to the principle that space is also moving. The universe has no center.
The universe contains everything in existence. It contains the largest galaxies and the smallest atoms. It formed 13.7 billion years ago in the Big Bang. Since then it is expending at an infinite scope.
The expanding of the universe was first observed in 1925 by the astronomer Edwin Hubble. He proved the direct relationship between the speeds of distance galaxies and their distances from Earth. This proof is now known as Hubble’s Law and the rate of cosmic expansion is called Hubble's Constant.