George Ellery Hale

George Ellery Hale built four of the world's largest telescopes in succession, each one pushing the boundaries of what could be observed. A solar astronomer by training, his true genius lay in fundraising, organization, and the vision to see what larger instruments could achieve. Hale founded the Yerkes Observatory with its 40-inch refractor (1897), then the Mount Wilson Observatory with its 60-inch (1908) and 100-inch Hooker (1917) reflectors. The 100-inch Hooker telescope enabled Edwin Hubble to discover that galaxies exist beyond the Milky Way and that the universe is expanding. Even as his health declined, Hale championed the 200-inch Hale Telescope on Palomar Mountain, completed in 1948 — a decade after his death. It remained the world's largest effective telescope for over 40 years. Hale also invented the spectroheliograph, discovered magnetic fields in sunspots, and founded the Astrophysical Journal.

• Built four successive world-record telescopes (Yerkes, 60-inch, 100-inch, 200-inch) • Founded Mount Wilson and Palomar Observatories • Invented the spectroheliograph for studying the Sun • Discovered magnetic fields in sunspots (1908) • Founded the Astrophysical Journal • His telescopes enabled Hubble's discovery of the expanding universe