| Henrietta Swan Leavitt (1868-1921) | | | | Cepheus. Leavitt became an accomplished variable |
| The discovery that forever changed our universe | | | | star hunter, cataloguing 2,400 such stars during the |
| came from a deaf American woman born on the 4th | | | | course of her work - more than half the total known |
| of July in 1868. Shortly after her graduation from what | | | | at the time. |
| we now call Radcliffe, an illness caused Henrietta | | | | In analyzing the plates, Leavitt began to notice the |
| Swan Leavitt to lose her hearing. The Harvard College | | | | brighter Cepheids exhibited a longer period of variability. |
| Observatory eventually hired her as a human | | | | Four years later, after further analysis, she surmised |
| "computer." Her job: review the hordes of glass | | | | the brightness of Cepheid Variables had a direct |
| photographic plates and calculate the brightness of the | | | | relationship with their period of variability. She deduced |
| stars in them. While reviewing a study of variable stars | | | | this relationship because all the stars in the Magellanic |
| in the Large and Small Magellanic Clouds (small satellite | | | | Clouds have the same distance from Earth. Since their |
| galaxies orbiting our own Milky Way) she developed a | | | | distance is known to be constant, their relative |
| fondness for the many Cepheid Variable stars within | | | | brightness can be directly compared. She published her |
| those two galaxies. A Cepheid Variable star dims and | | | | results in 1912. Unknown to all at the time, her discovery |
| brightens over a regular period, so named because, in | | | | would forever change our understanding of the |
| 1784, John Goodricke identified the first such example | | | | universe. |
| with the star δ Cephei in the constellation | | | | |