Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

June 21, 1998
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Edwin Hubble Discovers the Universe
Credit: Mt. Wilson Archive, Carnegie Institution of Washington

Explanation: No person in history has had greater impact in determining the extent of our universe than Edwin Hubble. From proving that other galaxies existed to proving that galaxies move apart from one another, Hubble's work defined our place in the cosmos. Hubble lived from 1889 to 1953 and is shown above posing with the 48-inch telescope on Palomar Mountain and his famous pipe. In memory of his great work, the Orbiting Space Telescope was named after him. The rate of the universe's expansion is now parameterized by a quantity known as Hubble's constant. A modern debate on the value of Hubble's constant took place in 1996.

Tomorrow's picture: A Doomed Dust Disk

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Technical Rep.: Jay Norris. Specific rights apply.
A service of: LHEA at NASA/ GSFC
&: Michigan Tech. U.