The Canada-France-Hawaii Telescope spotted the bright burst of light the black hole created as it sucked up nearby gas, heating it and causing it to glow very brightly in what's known as a quasar.
The distance to the quasar, which sits in the constellation Pisces, was determined by measuring the amount of redshift in the lines of the quasar's spectrum, or prism of light. Because light is "redshifted" to longer wavelengths as an object moves away from an observer, the higher the redshift, the further away the object is-and this quasar had quite a large redshift.
"As soon as I saw the spectrum with its booming emission line, I knew this one was a long way away," said team member Chris Willott of the University of Ottawa.
Because the Big Bang is believed to have occurred around 13.7 billion years ago, astronomers are seeing the quasar as it appeared a mere 1 billion years after the Big Bang, which gives them a unique view into universe's past.