What are the contributions of Edwin Hubble?

Edwin Hubble made significant contributions to astronomy, most notably through his discovery of the expansion of the universe, which led to Hubble's Law. He demonstrated that distant galaxies are moving away from us, with their speed proportional to their distance, providing strong evidence for the Big Bang theory. Hubble also played a crucial role in classifying galaxies and establishing the field of extragalactic astronomy. His work fundamentally changed our understanding of the universe and its structure.