NASA Celebrates Hubble’s Discovery of a New Cosmos

For us humans, the most important star in the cosmos is our own Sun. The second-most significant star is located inside the Andromeda galaxy. Don’t go looking for it — this flickering star and our earth are 2.2 million light-years apart. Yet, a century back, its discovery by Edwin Hubble (then an astronomer at Carnegie Observatories) opened humanity’s eyes as to how large the cosmos actually is, and exposed the fact that our Milky Way galaxy is just one among hundreds of billions of galaxies in the cosmos. This ushered in the coming-of-age for humans as a curious species that could scientifically ponder its own creation through the message of starlight. NASA and Carnegie Science are celebrating this centennial at the 245th meeting of AAS (the American Astronomical Society) in Washington, D.C.

Simply named V1, this seemingly inauspicious star flung open a Pandora’s box full of mysteries about space and time that are still challenging astrophysicists today. Hubble discovered the demure star in 1923 employing the largest telescope in the world at that time (the Carnegie-financed 100-inch Hooker Telescope). This rare kind of pulsating star, termed a Cepheid variable, is used as milepost markers for faraway celestial objects. There are no tape-measures available in space, but by the early 20th century Henrietta Swan Leavitt had found out that the pulsation period of Cepheid variables has direct connection with their luminosity.

The edge of our own galaxy (the Milky Way) marked the edge of the entire cosmos was the belief of astrophysicists for very long. But Hubble found that V1, nestled inside the Andromeda “nebula,” was at a distance that far exceeded anything in Milky Way galaxy. This led him to the jaw-dropping realization that the cosmos extends far beyond our own galaxy.

Actually, Hubble had suspected there was a larger cosmos out there, but here was the proof in the pudding. He was so astonished he scribbled an exclamation mark on the photographic plate of Andromeda that pinpointed the variable star. As a consequence, the science of cosmology exploded virtually overnight. Hubble’s contemporary, the eminent Harvard astronomer Harlow Shapley, upon Hubble notifying him of the discovery, was left devastated. “Here is the letter that destroyed my universe,” he lamented to fellow astronomer Cecilia Payne-Gaposchkin (who was present in his office when he opened Hubble’s message).

Just 3 years earlier, Harlow Shapley had presented his observational interpretation of a much smaller cosmos in a debate one evening at the Smithsonian Museum of Natural History in Washington. He maintained that the Milky Way galaxy was so massive, it must encompass the entirety of the cosmos. He insisted that the inexplicably fuzzy “spiral nebulae,” such as Andromeda, were simply stars forming on the periphery of our galaxy Milky Way, and insignificant.