Renowned 20th century astronomer Edwin Hubble’s groundbreaking discoveries fundamentally changed the scientific view of the universe and its origins. His meticulous studies of spiral nebulae proved the existence of galaxies other than our own Milky Way, and led to the realisation that the universe is expanding rather than static.
Named in his honour, the Hubble Space Telescope launched in 1990 has similarly enhanced our knowledge and understanding of the universe, enabling astronomers and scientists to see glimpses into the cosmos that Hubble himself would have been in awe of.
Here are 10 facts about Edwin Hubble, one of the most important figures in the field of modern astronomy.
1. He was a Rhodes Scholar
Edwin Hubble was born on 20 November 1889 in Missouri, and was a keen sportsman as well as a fan of science fiction novels. This fascination of the world around him led to him studying for a degree in maths and astronomy at the University of Chicago in 1906.
However, due to his father’s expectations, he went on to receive a scholarship to study at Queens College, Oxford University as a Rhodes Scholar, where he earned a degree in jurisprudence, including reading Roman and English Law. (The Rhodes scholarship is considered among the world’s most prestigious international scholarship programmes.)
Nevertheless, he longed to pursue a career in the sciences and later returned to the United States to obtain a PhD in astronomy from the University of Chicago in 1914 at the Yerkes Observatory.
2. He was a veteran of World War One
Hubble had hoped to finish his doctoral dissertation on a photographic investigation of faint nebulae and take up a position at the Mount Wilson Observatory in the summer of 1917, yet by then America had entered World War One.
He rushed through his dissertation, took a final oral exam and reported to the army for duty just three days later. Hubble served in the US Army in France as a member of the 86th Division, reaching the rank of major, yet the 86th Division never saw combat.
(During World War Two he served in an administrative capacity at the Aberdeen Proving Grounds in Maryland.)
3. He was a key member of the Mount Wilson Observatory in California
Completed in 1917, the Mount Wilson Observatory’s 100-inch (2.5 metre) Hooker telescope was the world’s largest at the time (until 1949).
In 1919, Hubble was offered a staff position at the observatory by its founder and director, George Ellery Hale. Hubble went on to use the telescope to make many of his most important observations, and remained on staff at Mount Wilson until his death in 1953.
4. He is credited with the discovery of galaxies outside the Milky Way
At that time, the prevailing view of the cosmos was that the universe consisted entirely of the Milky Way Galaxy. Although astronomers had speculated about the existence of other galaxies in the universe, there was no observable evidence of them. When Hubble pointed the Hooker Telescope at the constellation Andromeda Nebula, this perspective shifted.
For centuries, the Andromeda Nebula had appeared as just an elongated cloud of light, dust and gas. But by using the telescope to observed these faint, fuzzy, cloud-like patches of light, Hubble’s observations now brought them into focus. In 1923, Hubble discovered that there were individual stars in this nebula.
Hubble’s continued observations uncovered his first Cepheid variable star – a type of star used to measure distances in space by how its brightness changes. By charting the changes in these stars, Hubble discovered that the Cepheid variable stars in Andromeda were much further away than those in the Milky Way, leading him to believe the Andromeda Nebula was a galaxy in its own right.
Hubble used this technique to study other spiral ‘nebulae’ in the universe, and concluded that millions of galaxies existed beyond our own. This discovery expanded the known size of the universe by several orders of magnitude, transforming the field of cosmology.
5. He devised the Hubble Classification Scheme
Hubble compared galaxies by studying their physical properties. Focusing on their visual appearance, Hubble devised what is now the most influential system for classifying galaxies: the Hubble Classification Scheme. This arranges galaxies into two main categories based on their shapes – elliptical or spiral – and is subdivided based on specific characteristics of each galaxy.
This sequence helped lay the groundwork for understanding how galaxies evolved, and ultimately the formation of the universe.
6. He developed the Hubble-Lemaître law, which describes the expansion of the universe
By 1929, Hubble had discovered that not only was the universe home to millions of other galaxies, but the universe itself was expanding. He published a paper (‘A Relation Between Distance and Radial Velocity Among Extra-Galactic Nebulae’) that demonstrated that the further away a galaxy is from Earth, the faster it is moving away from Earth.
Thus while other scientists – including Einstein – had assumed the universe to be static, Hubble went on to show that the universe is expanding. This notion of an ‘expanding’ universe formed the basis of the Big Bang theory, which states that the universe began with an intense burst of energy at a single moment in time and has been expanding ever since.
Hubble had changed our view of the universe forever, finding that our own vast galaxy, home to our sun and 100 billion other stars, is but one of billions of other galaxies.
7. He was the first astronomer to use the term ‘redshift’
Furthermore, by studying the light emitted from various galaxies, Hubble discovered the shift in the spectrum of light from distant galaxies towards the red end of the spectrum. It became apparent that the universe was continuously expanding outward, and all the galaxies within it were moving away from one another. Hubble deemed this process ‘redshift’, as the further a galaxy is away from Earth, the redder its light will appear.
This shift is caused by the Doppler effect and is another key piece of evidence for the expansion of the universe.
8. Einstein thanked Hubble for his work
More than a decade prior to Hubble’s discoveries, Albert Einstein had set out his general relativity theory, and produced a model of space based on it, which claimed that space was curved by gravity and must therefore be capable of expansion and contraction. However, Einstein had caved to the observational wisdom of the day and changed his original equations. With the discovery of Hubble’s Law, Hubble had proved Einstein right.
Einstein paid a special visit to Hubble at Mount Wilson in 1931 to thank him for his work, stating that second-guessing his original findings had been “the greatest blunder of my life”.
9. He received numerous awards and honours
Hubble received a large number of awards in his lifetime, including the Newcomb Cleveland Prize in 1924; the Bruce Medal in 1938; the Franklin Medal in 1939; and the Gold Medal of the Royal Astronomical Society in 1940. (He also received a 1946 Medal of Merit for outstanding contribution to ballistics research during World War Two.)
Posthumously, Hubble also gained many honours. ‘Asteroid 2069 Hubble’ discovered in 1955, is named after him, as is the Hubble crater on the Moon.
10. The Hubble Space Telescope is named in his honour
Hubble died in 1953 aged 63, leaving an immense legacy. His discovery of galaxies outside the Milky Way and the expanding universe revolutionised our understanding of the cosmos and continue to shape our understanding of the universe today.
In recognition of his contributions, the Hubble Space Telescope, launched in 1990, was named in his honour. This telescope, removed from Earth’s atmosphere, now serves as our window to the universe. It is not the first space telescope, but it is one of the largest and most versatile, renowned both as a vital research tool and as a public relations boost for astronomy due to the stunning images it brings us.