For more than a decade, a galaxy named HDF 850.1 has perplexed astronomers. At the far-infrared wavelength of 850 microns, this galaxy is the brightest
object in the Hubble Deep Field, a long exposure the Hubble Space Telescope
took in December 1995 (left image). But at optical wavelengths, HDF 850.1 (right image) is invisible; no one even knew how far it was from Earth. Today,
astronomers report online in Nature the first detection of HDF 850.1's redshift—a measure of its distance—at radio wavelengths. The redshift
is 5.183 and means the galaxy is 12.6 billion light-years away, so we see it just 1.1 billion years after the big bang.
HDF 850.1 is a "starburst," spawning stars hundreds of times more intensely than the Milky Way, but the galaxy is so shrouded in dust that not even
hawk-eyed Hubble can glimpse the light of its many newborn stars.
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