The Hubble Legacy
Edwin Hubble and Harlow Shapley immediately butted heads when Hubble began his work with the 100-inch. Hubble had studied Fath’s and Curtis’ work, and was convinced they were correct in their assessment of the nature of the “island universes." Shapley, on the other hand stood stoically with the traditional view that the Milky Way was “the universe" and all the nebulae, while perhaps huge star clusters, resided within it.
Edwin Hubble was not to be swayed, however, and he was convinced he knew how to prove Fath’s and Curtis’ theories. One of the first objects he turned the giant 100-inch on was M31—the great nebulae in Andromeda. The big telescope easily resolved the “ghostly cloud" into its collection of stars. But that didn’t prove it was not within the Milky Way. To do that, Hubble had to measure the distance to M31.
Shapley himself had paved the way for Hubble to do that.
Hubble searched for Cepheid variables in Andromeda, and found one. With that, he could measure its distance. His figure was one million lys. We now know that’s less than half the actual distance. Both Hubble’s and Shapley’s measurements were off because they did not know at the time the light they were measuring was being filtered and dimmed by dust and gas clouds in the Milky Way. Still, it was clear the “nebulae" was far outside the Milky Way. It was, without question, a separate collection of stars in itself.
With that evidence, Hubble turned the 100-inch on other Messier objects. They, too, were separate collections of stars, each further away than Andromeda.
The universe had suddenly become much larger.
As the evidence compounded, even Shapley had to grudgingly accept it. In the end, he coined the term “galaxy" for the giant collection of stars previously called nebula. But Hubble, still chaffing from Shapley’s long resistance to his theories about the universe, refused to use the word, and continued to call them nebulae.
Hubble noticed something else as he continued to look at galaxies further away. The further away they were, the redder their light was. It was known as red shift. Just as a train whistle seems to sound lower as it moves away from you, light seems to shift lower in frequency—towards red—when an object is moving away. The faster the object is moving, the greater the shift towards the red. That could mean only one thing—the galaxies were moving away from us, and the further away they were, the faster they were moving.
And that could mean just one thing. The universe was expanding.
But expanding from what?
It would take other astrophysicists to unravel this puzzle. Using Hubble's data, Georges Lematres posited that the universe began from a tiny "atom" that exploded outward. Hubble agreed. Years later, Fred Hoyle, a well respected astrophysicist who totally rejected this theory, sarcasticly called it the Big Bang theory. His term stuck.
It would take another generation of astrophysicists to prove Lematres and Hubble right on this, but today they have, and the Big Bang is the basis of any and all theories on the origin of the universe.
Edwin Hubble discovered galaxies, and his legacy continues today, 220 miles above the Earth, with his namesake, the Hubble Space Telescope. It, like the man throughout his lifetime, continues to make discoveries that change the face of astronomy.