Astronomers on Wednesday said they had snared an image of what may be the oldest galaxy ever seen, a starry cluster that came into being when the Universe was still a baby. The tiny smudge of light captured by the orbiting Hubble telescope took 13.2 thousand million years to reach Earth, which means the galaxy was born some 480 million years after the "Big Bang" that created the cosmos.
Even older galaxies are likely to be out there, but they will only be detected with next-generation sensors aboard the Hubble's successor, they said. "We're getting back very close to the first galaxies, which we think formed around 200 to 300 million years after the Big Bang," said Garth Illingworth, professor of astronomy and astrophysics at the University of California at Santa Cruz.
Astronomers measuring the age of starlight look for something called redshift: the farther that light travels, the longer and "redder" become its wavelength. A high redshift number thus indicates that the object is old, for the light it emitted has taken billions of years to reach us across the expanding Universe.
The new-found galaxy, UDFj-39546824, was found in a fingernail-sized sector of sky called the Hubble Ultra-Deep Field during 87 hours of scans in 2009 and 2010. Its finders calculate the redshift as a whopping 10.3, far older than the previous record for a galaxy of 8.6, announced by an international team last October.
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