It's been 100 years since we learned the Milky Way is not the only galaxy

On Sunday November 23, 1924, 100 years ago this month, readers perusing page six of the New York Times would have found an intriguing article, amid several large adverts for fur coats. The headline read: Finds Spiral Nebulae are Stellar Systems: "Dr. Hubbell Confirms View That They Are 'Island Universes'; Similar to Our Own."