Astronomers on Thursday posted a spectacular image using 16 years’ worth of Hubble Space Telescope data. The image contains about 265,000 galaxies.
The Hubble Legacy Field (HLF) mosaic image combines observations from 16 years’ worth of Hubble Space Telescope deep-field surveys, including the eXtreme Deep Field (XDF) survey, which offers the most far-reaching view of the universe.
By assembling a mosaic of nearly 7,500 images of one part of the sky, astronomers have created the largest and most comprehensive ‘history book’ of the universe.
“Now that we have gone wider than in previous surveys, we are harvesting many more distant galaxies in the largest such dataset ever produced by Hubble,” said Dr. Garth Illingworth, an astronomer at the University of California, Santa Cruz.
“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’.”
You can see about 265,000 galaxies, packed into a region smaller than the moon’s apparent size in the sky. They stretch back through 13.3 billion years of the universe’s history, to just 500 million years after the big bang.
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Galaxies in the new image are just one ten-billionth the brightness of what the human naked eye can see.
“Hubble has looked at this area of the sky many times over many years, and now we have combined all these photographs into a single, very high-quality, wide-angle image. It is like having a history book of the universe in one image,” said Pieter van Dokkum, the Sol Goldman Family Professor of Astronomy at Yale and co-investigator on the team that assembled the image.
The project started in 1995 when the telescope captured its first and famous Hubble Deep Field image. To create that image, Hubble focused on one of the darkest patches of the night sky. The telescope observed that part of the sky over 10 days, snapping more than 340 photos.
The HLF image contains 100 times as many galaxies as the previous deep-field surveys. That’s because it takes in a wider view.
The image comprises the collective work of 31 Hubble programs by different teams of astronomers.
Meanwhile, the HLF team is working on the second set of images that will include more than 5,200 Hubble images. But this time astronomers will be focusing on another area of the sky. It sets the stage for NASA’s planned Wide-Field Infrared Survey Telescope, which will explore an even wider area of space than HLF.