2 minute read
Edwin Hubble
The astronomer whose studies of DISTANT GALAXIES expanded our understanding of the UniverseEd w in Hu b ble
Hubble proved that we live in a Universe of billions of galaxies, and that it is rapidly expanding.
Advertisement
Change of direction
Born in Missouri, USA, in 1889, Edwin Hubble was a high school teacher and then a lawyer before turning to astronomy. After gaining a PhD, he served in World War I and then started a research job at the MOUNT WILSON OBSERVATORY in California in 1919.
Who came before...
In 1750, English astronomer Thomas WrighT was the first to describe the shape of the Milky Way. He speculated that faint cloudy spots, or nebulae, could be distant galaxies. American astronomer VesTo melVin slipher researched on galaxy red shifts between 1912 and 1925. His work showed that most galaxies are moving away from Earth, paving the way for Hubble’s Law.
By the way… I was a talented boxer but turned down the opportunity to become a professional.
Did you know? Hubble’s method of classifying galaxies, based on their shape, is still in use today.
Hubble used the Hooker Telescope at the Mount Wilson Observatory.
Beyond the Milky Way
At the time, astronomers believed the Milky Way made up the entire Universe. However, while studying a cluster of stars, Hubble identified a CEPHEID VARIABLE – a giant star that gets brighter and dimmer with time. Using Henrietta Swan Leavitt’s period-luminosity relation, he worked out that this star was actually about a million light years away and part of an entirely separate galaxy to our own. The red shift effect is a sign that a star is moving away from us.
As a star moves further away, its light appears redder.
Hubble’s Law
As a light source moves away from an observer, the wavelengths of light are stretched, producing red light. Astronomers noted this RED SHIFT EFFECT in the wavelengths of distant stars – a sign that these stars and their galaxies are moving away from Earth. Hubble realized that the more distant a galaxy, the greater its speed. Known as Hubble’s Law, this provided the first proof that the Universe is expanding.
How he changed the world A Cepheid variable glows brighter than the stars around it. Hubble’s discovery that there are galaxies outside our own profoundly changed our view of the Universe. His research led to the realization that space is expanding and laid the groundwork for the Big Bang theory.
What came after...
The Hubble Constant is the measurement unit that describes the Universe’s expansion. American astronomer Allan Sandage played a key role in determining it. Launched in 1990, the Hubble spaCe telesCope orbits Earth every 97 minutes. Beaming back images of distant galaxies, it has peered at regions 13.4 billion light years away.
