Ten years of images from the Hubble space telescope have been combined for the best, deepest-ever view of the universe, U.S. and European astronomers say. The photo, assembled by combining a decade of NASA/European Space Agency Hubble observations of a patch of sky within the original Hubble Ultra Deep Field, has been dubbed eXtreme Deep Field or XDF, the Hubble European Space Agency Information Center in Munich, Germany, reported Tuesday. Collating images collected through long years of observation, the resulting image reveals about 5,500 galaxies, both nearby and very distant, making it the deepest image of the Universe ever taken. \"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 the University of California, Santa Cruz, principal investigator of the Hubble Ultra Deep Field 2009 program. The universe is 13.7 billion years old, and the XDF reveals galaxies going back 13.2 billion years in time. \"XDF allows us to explore further back in time than ever before,\" Illingworth said. Before Hubble was launched in 1990, astronomers had been able to see galaxies as much as 7 billion light-years away, just halfway back to the big bang.