In the 1920s the American astronomer Edwin Hubble was the first to prove that there are galaxies outside the Milky Way.
By using Cepheid variable stars to calculate the distance of the Andromeda Nebula (as it was then known) from the Earth, Hubble showed that it was a separate galaxy and not a gas cloud in the Milky Way. Later, by comparing the relative velocities of galaxies (measured as red shifts) with his measurements of their distances from the Earth, Hubble showed that the further away a galaxy is from any point in space, the faster it appears to move because of the expansion of the Universe – Hubble's Law.
Image: Hubble at Palomar Observatory (credit: Emilio Segre Visual Archives/AIP/SPL)
This clip was filmed at a time when the Hubble Space Telescope had been discovered to have a flawed mirror, hence the reference to "failure". The Hubble Space Telescope went on to become one of the most successful NASA missions. This clip looks at some of the American astronomer Edwin Hubble's most important contributions to astronomy and the equipment he used at the Mount Wilson Observatory. The age of the Universe is now thought to be 13.7 billion years.
Sir Patrick Moore's guest Professor Richard Ellis from the University of Oxford reviews the world's large observatories and explains their importance. [The black and white images of Edwin Hubble, George Hale, Mount Wilson, the 200-inch telescope and mirror making in this clip are copyright Palomar Observatories/Caltech]
Edwin Hubble discovers galaxies outside the Milky Way and measures how far away they are.
Edwin Powell Hubble (November 20, 1889 – September 28, 1953) was an American astronomer who is known for Hubble's law. He is incorrectly credited with the existence of galaxies other than the Milky Way and galactic red shift- discoveries made by the astronomer Vesto Slipher in 1912. He popularized Vesto Slipher's discovery that the loss in frequency—the redshift—observed in the spectra of light from other galaxies increased in proportion to a particular galaxy's distance from Earth. This relationship which was based Slipher's data became known as Hubble's law. Vesto Slipher, the unsung hero of twentieth-century astronomy was the first to present his findings in a meeting of the American Astronomical Society in August 1914. Stephen Hawking wryly notes in his book the Universe in a Nutshell "Hubble heard the presentation". Due to Vesto Slipher's reserved and reticent personality, his discoveries are incorrectly credited to Hubble.
Hubble doubted the Doppler shift interpretation of the observed redshift that had been proposed earlier by Vesto Slipher, whose data he used, and that led to the theory of the metric expansion of space. He tended to believe the frequency of any beam of light could, by some so far unknown means, be diminished ever stronger, the longer the beam travels through space.
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