Garth Illingworth, principal investigator of the 2009 Hubble Ultra Deep Field programme, said most of the galaxies in the XDF image are young, small, and growing, often violently as they collide and merge together. “The early Universe was a time of dramatic birth for galaxies containing brilliant blue stars far brighter than our Sun. The light from those past events is just arriving at Earth now, and so the XDF is a time tunnel into the distant past when the Universe was just a fraction of its current age. The youngest galaxy found in the XDF existed just 450 million years after the Universe’s birth in the Big Bang,” he explained.
Illingworth said these baby galaxies are tiny and faint in the image, but nevertheless are the seedlings from which today’s 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 remarkable image,” he said.
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