Cosmic Times

Cosmic Times

Age of the universe:
2 billion years
Size of the universe:
280 million light years

Universe is Expanding

Hubble diagram

Using the 100-inch Hooker Telescope at Mount Wilson Observatory, Dr. Edwin Hubble has studied many spiral nebulae. He has discovered they are moving away from us at a rapid pace. This is strong evidence of an expanding universe. He has further determined that the farther the nebula, the faster it moves away.

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The Minds atop Mount Wilson

Mount Wilson 100-inch Hooker telescope

High above Pasadena, California in the San Gabriel Mountains, the astronomers at the Carnegie Institution's Mount Wilson Observatory are changing our view of the Universe. Who are these scientists?

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Classifying Nebulae

Hubble 'tuning fork' diagram of galaxy classification

For over a thousand years, astronomers wondered about the nature and development of nebulae. Nebulae appear to be faint clouds of gas and dust in the distant universe. Until recently, there have not been enough observations to classify nebulae based on their features or qualities.

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In Their Own Words

Image of Albert Einstein Image of Edwin Hubble

Read quotes from Albert Einstein and Edwin Hubble about our changing understanding of the universe.

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Andromeda Nebula Lies Outside Milky Way Galaxy

annotated image of Andromeda showing variable star locations

Astronomer Edwin Hubble, of the Mount Wilson Observatory at Pasadena, California, has solved the mystery of the spiral nebulae. The spiral nebulae look like hazy pin-wheels in the sky. He has determined that these objects are much more distant than previously thought. Therefore, they are distant galaxies and not part of our own Milky Way galaxy. In the process, Dr. Hubble was also able to determine the distance to the spiral Andromeda nebula.

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"Great Debate" Resolved

Image of Heber Curtis Image of Willem de Sitter

Dr. Hubble's discovery settles the "Great Debate" over the size of our own Milky Way galaxy. It also settles the distance to spiral nebulae and what they are.

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Image of the 1929 Cosmic Times poster

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A service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Andy Ptak (Director), within the Astrophysics Science Division (ASD) at NASA/GSFC