Part 3/11:
Advancements continued into the 18th century when William Herschel mapped stars within our galaxy—the Milky Way—revealing it as a vast, disk-shaped stellar system. Yet, it took the revolutionary work of Edwin Hubble in the early 20th century to establish that the universe is far larger than we had imagined. Using the 100-inch Hooker Telescope, Hubble identified individual stars in the Andromeda Galaxy and, through their variable star types, measured distances that confirmed Andromeda as a separate galaxy outside our Milky Way. This discovery expanded our cosmic horizon exponentially, revealing a universe teeming with countless galaxies.