NASA's Hubble Space Telescope reveals nearly 10,000 galaxies in the deepest visible-light image of the cosmos. The Hubble Ultra Deep Field, taken by the Advanced Camera for Surveys, represents a 'deep' core sample of the universe. There are galaxies of various ages, sizes, and colours. The smallest, reddest galaxies may be among the most distant known, existing when the universe was 800 million years old. The larger and brighter galaxies thrived about 1 billion years ago, when the cosmos was 13 billion years old. Blue and green correspond to colours seen by the human eye. Red represents near-infrared light - invisible to the human eye. The image required 800 exposures over the course of 400 Hubble orbits around Earth. The total exposure time was 11.3 days, between 24 September 2003 and 16 January 2004.
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