# Hubble's Island Universes: Andromeda's Cosmic Distance Revealed
Published: December 30, 2025
Duration: 1:45
# Astronomy Tonight Podcast
This is your Astronomy Tonight podcast.
On December 30th, we celebrate one of the most dramatic and consequential discoveries in the history of astronomy: the identification of Cepheid variables in the Andromeda Galaxy by Edwin Hubble in 1924!
Picture this: it's the roaring twenties, and Edwin Hubble is peering through the 100-inch Hooker Telescope at Mount Wilson Observatory in Southern California. For centuries, astronomers had debated whether the fuzzy "nebulae" they observed through their telescopes were merely clouds of gas within our own Milky Way, or something far more extraordinary—entire island un...
This is your Astronomy Tonight podcast.
On December 30th, we celebrate one of the most dramatic and consequential discoveries in the history of astronomy: the identification of Cepheid variables in the Andromeda Galaxy by Edwin Hubble in 1924!
Picture this: it's the roaring twenties, and Edwin Hubble is peering through the 100-inch Hooker Telescope at Mount Wilson Observatory in Southern California. For centuries, astronomers had debated whether the fuzzy "nebulae" they observed through their telescopes were merely clouds of gas within our own Milky Way, or something far more extraordinary—entire island un...