From Twitter https://twitter.com/drsekula:

RT @coreyspowell: 93 years ago #today, Hubble revealed proof that our galaxy is just one of a vast multitude. http://history.aip.org/history/exhibits/cosmology/ideas/island.htm https://twitter.com/coreyspowell/status/833429453564841984/photo/1 https://chirp.cooleysekula.net/attachment/22956