A Decade of Discovery
All About Hubble

Astronomers used NASA's Hubble Space Telescope to look out into the universe over distances exceeding 12 billion light-years. These "deepest" views of the heavens, made with Hubble's visible and infrared cameras, are collectively called the Hubble Deep Field.

Because the starlight harvested from remote objects began its journey toward Earth billions of years ago, Hubble, as well as all large telescopes, look farther back into time the farther they look into space. Hubble has seen back to a time when the universe was only about five percent of its present age. These "long exposures" of the universe have revealed galaxies that existed when the universe was less than one billion years old. Some of the objects viewed were so dim that seeing them would be as difficult as discerning a flashlight on the Moon as seen from Earth.

The Deep Field uncovered more than 1,000 galaxies in a patch of sky no larger than a grain of sand held at arm's length. Extrapolated across the entire sky, this means the universe contains at least 120 billion galaxies. These thousands of galaxies are at various stages of evolution and are strung along a corridor of billions of light-years.

Hubble's high resolution enables astronomers to actually see the shapes of galaxies in the distant past and study how they have evolved over time. They found that galaxies looked more fragmentary in the distant past and took time to evolve to the majestic spirals and giant elliptical galaxies of today. They also found that the universe formed most of its stars when it was less than half its present age. Astronomers will spend years sorting the myriad shapes of the galaxies in this image to understand how they formed and how have evolved since the Big Bang.

A variety of other telescopes, with sensitivities ranging from X-rays to radio waves, have also been aimed at the Deep Field to see if astronomers can match various astronomical phenomena to the visible-light galaxies.

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