Edwin Hubble was an American astronomer who made vital contributions to the study of galaxies, establishing the existence of galaxies outside of the Milky Way and proving that the universe is expanding. For his revolutionary contributions to our understanding of galaxies and of the scope of the universe, Hubble was recognized by the astronomical community in 1983, thirty years after his death, when the Space Telescope was renamed in his honor.
Edwin Powell Hubble was born on November 20, 1889 in Marshfield, Missouri before the eyes of both his parents and his grandparents. At a young age, Hubble had a taste for books and an interest in astronomy, unlike many of the other great astronomers portrayed in these biographies.
A strong athlete in high school, Hubble received a scholarship from the University of Chicago but had to work hard nonetheless to pay the balance of his expenses. Perhaps his most interesting job during this time was as a lab assistant to Robert Millikan -- well known for determining the charge of an electron in his Nobel prize-winning oil drop experiment.
Hubble received his B.S. degree from the University of Chicago and was offered a Rhodes Scholarship to study law at Queens College in Oxford. Though Hubble started a law practice after returning to the United States, he abandoned his practice and returned to Chicago to study for his doctorate in astronomy, which he received the day before joining the army in 1917.
It is difficult to find a photograph in which Edwin Hubble is not seen poised on a mammoth telescope in an observatory. From the time he began his doctorate work at the University of Chicago's Yerkes Observatory in 1914 to his death, Hubble worked with many observatories and was influential in the construction of the largest ground-based telescope in the world.
Mount Wilson. After the First World War, Hubble was married to Grace Burke and began work at the Mount Wilson Observatory with its 100-inch telescope. Above all, his research there demonstrated the need for a larger telescope that could see farther. Hubble left Mount Wilson in 1942, off again to war, where he would be awarded a Medal of Merit in 1946, and returned again after the war to continue his research.
Mount Palomar. Most of Hubble's work was done at the Mount Wilson Observatory, but he was intimately involved with the Mount Palomar Observatory, part of the committee that oversaw its construction. Even more importantly, he advised and assisted in the construction of the Mount Palomar 200-inch Hale telescope, where he can be seen perched in photos.
In the early 20th century, before Hubble began his extensive work, there was an intense debate raging in the field of astronomy over great clusters of stars, called "nebulae." At the time, there was no evidence that there were galaxies in the universe that lay beyond the Milky Way. At issue, then, was whether these "nebulae" were a part of the Milky Way or some other star formations beyond our galaxy. In some ways, it is more difficult to comprehend that the existence of other galaxies was uncertain in such recent years than to believe that Copernicus was doubted in the 16th century for proposing the idea of a solar system.
Finally, Hubble determined that these "nebulae" are indeed other galaxies because they are moving away from the earth. In fact, he concluded that these star systems are each "island universes," not part of our own galaxy. This was an enormously important discovery, for it opened up a great new realm of research and provided an important base for the theory of the expanding universe.
When Hubble observed other galaxies moving away from Earth, he was looking at the wavelengths of their light. If the wavelengths are longer and towards the red end of the spectrum, then the galaxy is going away from us; but if the wavelengths are shorter and bluish, then the galaxy is coming towards us. Later in the Guided Tour, we will expand on the concepts of "redshifting" and "blueshifting." For now, it is enough to understand that he could prove that these galaxies were moving away from Earth.
Diagram. Red shift and Blue shift. Hubble used the wavelengths of light to determine whether galaxies were moving towards or away from us. Galaxies with wavelengths in the red regions are moving away while those with wavelengths in the blue regions are coming towards us. Original diagram by The Online Planetarium Show.
Another interesting aspect of Hubble's research was his discovery that more distant galaxies move away more quickly than those closer to us. The very notion that these galaxies were actually receding is an important one because it is a central tenant of the Big Bang theory, in which a powerful explosion initiates the inflation of the universe. Incredibly, Albert Einstein referred to Hubble's work as "beautiful" and adjusted his relativity equations to account for the fact that the universe is expanding!
Hubble's work classifying galaxies is hardly unimportant, yet it pales in comparison with his far-reaching discoveries. Hubble grouped galaxies into three main categories:
Ever since, astronomers have been identifying galaxies as either spiral, elliptical or irregular. Though we regularly use these terms to describe galaxies and though this terminology is exceedingly important to astronomy, Hubble's name is only rarely mentioned, much less associated with these classifications.
When we speak of the telescope, Galileo's name frequently surfaces, for he popularized the instrument for astronomical purposes. For all of Edwin Hubble's incredible discoveries that are discussed in this biography -- particularly his proof of the very existence of galaxies outside of the Milky Way -- it would seem that the leaps in astronomy's understanding of the universe made by his work are comparable to those made by the studies Galileo or Copernicus.
Yet for all of his accomplishments, Hubble's name is relatively obscure; even when we hear about the Space Telescope that was named in his honor, we rarely learn about his contributions or life. According to several biographers, he should be looked upon as an astronomer who "revolutionized" our understanding of the universe -- much like Galileo or Copernicus. Perhaps in several hundred years we will.