Astronomers have created the largest and most comprehensive "history book" of 265,000 galaxies into one single image, stretching back through 13.3 billion years of time to just 500 million years after the big bang.

They used 16 years of observations from the U.S. space agency NASA's Hubble Space Telescope, chronicling the universe's evolutionary history in one sweeping view, with nearly 7,500 exposures.

The portrait shows how galaxies change over time, building themselves up to become the giant galaxies, and the faintest and farthest galaxies are just one ten-billionth the brightness of what the human eye can see, according to a press release of NASA this week.

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Galaxies allow astronomers to trace the expansion of the universe, offer clues to the underlying physics of the cosmos, show when the chemical elements originated, and enable the conditions that eventually led to the appearance of our solar system and life.

"This one image contains the full history of the growth of galaxies in the universe, from their time as 'infants' to when they grew into fully fledged 'adults'," said Garth Illingworth of the University of California, Santa Cruz, leader of the team that assembled the image.

This new image mosaic is the first in a series of Hubble Legacy Field images. The team is working on a second set of images, totaling more than 5,200 Hubble exposures, in another area of the sky.

Xinhua

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