Whose discovery was the expanding universe?

In 1929 Edwin Hubble, using the large telescope at Mount Wilson, found that galaxies are moving away from us and that the farther a galaxy is, the faster it recedes. This relationship, now called Hubble law, showed that the universe is expanding rather than static. Earlier, the Belgian priest and physicist Georges Lemaitre had proposed an expanding universe on theoretical grounds. Hubble observations transformed cosmology and led to the idea that the universe began in a hot, dense state, the Big Bang. The rate of expansion is known as the Hubble constant.