The Edge of the Universe
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|Padraig Reed||September 28th 2012|
From VOA, NASA, and ESA
|Hubble XDF image (credit: NASA; ESA; G. Illingworth, D. Magee, and |
P. Oesch (UC Santa Cruz); R. Bouwens (Leiden University); and
the HUDF09 Team)
NASA’s Hubble space telescope has captured the deepest view to date of the universe, a photograph showing galaxies going back almost to the beginning of time. Hubble’s latest view of the universe, called the eXtreme Deep Field (XDF), is a photograph combining 10 years of data and showing about 5,500 galaxies, the oldest of which is about 13.2 billion years old. The universe is estimated to be about 13.7 billion years old.
“The XDF is the deepest image of the sky ever obtained and reveals the faintest and most distant galaxies ever seen,” said Garth Illingworth of UC Santa Cruz, a scientist working on the project. “XDF allows us to explore further back in time than ever before.”
The XDF image is even more detailed than the original Hubble Ultra Deep Field image, thanks to the additional observations, and contains about 5500 galaxies, even within its smaller field of view. The faintest galaxies are one ten-billionth the brightness that the unaided human eye can see. Hubble repeatedly focused on a tiny patch of southern sky during the past decade, with a total exposure time of two million seconds. More than 2000 images of the same field were taken with Hubble’s two primary cameras, which were then combined to form the XDF.
NASA described the XDF photograph as a “time tunnel into the distant past,” explaining that the light from those distant galaxies was “just arriving at the earth now.” It said one of the galaxies in the photograph existed just 450 million years after the universe began with the big bang. Before Hubble, astronomers using Earth-based telescopes could see galaxies up to 7 billion light years away, or about halfway across the known universe.
Magnificent spiral galaxies similar in shape to the Milky Way and its neighbor Andromeda appear in this image, as do large, fuzzy red galaxies in which the formation of new stars has ceased. These red galaxies are the remnants of dramatic collisions between galaxies and are in their declining years as the stars within them age.
Peppered across the field are tiny, faint, and yet more distant galaxies that are like the seedlings from which today’s magnificent galaxies grew. The history of galaxies—from soon after the first galaxies were born to the great galaxies of today, like the Milky Way—is laid out in this one image.