One of my favourite pieces of science communication written by any scientist is Hubble’s “The Exploration of Space”. It was written in 1929 and published in Harper’s Magazine (158: 732) for the general public. I find it absolutely fascinating, but I’ve come to realise that the people who are not as familiar with astrophysics as I am might not realise that some of the things said in the piece are no longer correct, due to more recent discoveries. So I’ve created an annotated version, hoping to clarify most of the points, and to illustrate how science is a journey of receding horizons from partial truth to (slightly wider) partial truth.