Edwin Hubble proved that there are other galaxies spread throughout the universe, and that these galaxies move away from each other as the universe expands. The findings even startled Einstein. He further found that the galaxies in the outermost areas of the universe move faster that those nearer the middle, a feature in his Hubble's Law.
The famous Hubble Telescope, named in his honor, was carried into orbit by the space shuttle Discovery on April 25, 1990, more than 35 years after his death. It is the most sensitive optical telescope constructed at that time.
Early Life of Edwin Hubble: from Law to Astronomy
Hubble was born on November 20, 1889, in Missouri and then his family moved to Chicago when he was nine. He was athletic, with a high-jump record, and a member of a basketball team. He got a Rhodes scholarship, chose Oxford to study law, as he promised his dying father. He practiced law at Kentucky, but interest in astronomy beckoned.
When World War I broke out, his desire to study astronomy was postponed. He served the war in France and Germany, becoming a major. After the war, he worked at a leading observatory, at Mount Wilson Observatory near Pasadena, California, where the Hooker telescope was being used, the biggest in the world that time, with a massive 100-inch mirror.
Hubble's Early Work on Galaxies
Earth orbits the Sun, along with the other planets making up the solar system. However, the Sun is only a part of some hundred billion stars, with their own solar systems, that make up our galaxy.
Hubble started taking photographs of one particular cloud-like patch of light that appears about the size of the Moon. Called the Andromeda nebula (Latin for 'cloud'), no one was sure what this mass was. In 1923, Hubble saw bright points of light flaring within the Andromeda nebula. They looked like novae, stars that eject part of their materials and increase their brightness. Further study showed Hubble that these objects' lights flared on a regular cycle. This was a critical breakthrough.
Nebulae Classifications
Hubble wasn’t the first person to suggest that nebulae were separate galaxies, but he was the first to produce proof. The most extensive survey of the sky about star clusters and nebulae had been carried out in the 18th and 19th centuries by Caroline Herschel, her brother Frederick William Herschel, and his son John Herschel, who published their collection in his Philosophical Transactions.
A contemporary of Hubble, German astronomer Maximilian Franz J.C. Wolf, started to classify some clusters using a telescope at Heidelberg.
The Expanding Universe Concept
With fellow astronomer and American Vesto Slipher they studied the speed (velocity) at which the nebulae moved relative to the Earth. Slipher was the first to discover red-shifts in the spectrum of the Andromeda galaxy.
Hubble continued work to measure the distance between the Earth and the galaxies he identified. He was on his way to discovering and predicting more the expanding universe.
In the 1920s Hubble published his Ph.D and presented an outline concept of a new way of classifying galaxies.
More Galaxies Discovered by Hubble
Two years later, Edwin Hubble married Grace Burke. At the same time he announced his discovery of a Cepheid variable in the Andromeda nebula. By studying Cepheid variables, he proved that there are other galaxies outside our own galaxy. The variable points of light he saw in the Andromeda nebula outside the milky way were Cepheid variable stars.
Last years of EDwin Hubble
Hubble left the observatory to do war work at the Aberdeen Proving Ground. He was awarded a Medal of Merit then returned to the Mount Wilson and Palomar Observatories. He died on September 28, 1953, in San Marino, California.
Sources:
E=Mc2, the Great Ideas that Shaped our World, by Pete Moore, Quintet Publishing (2002)
Who Discovered What When, by David Ellyard, New Holland (2005)
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