Astronomers say they've discovered massive galaxies that may have produced stars as early as 1 billion years after the Big Bang. Scientists used the Atacama Large Millimeter/submillimeter Array in Chile to study 26 star-making galaxies, which may be some of the oldest-known in the universe. "These types of galaxies, which are massive dusty galaxies that are forming stars -- these are the most active locations of star formation in the universe," said Joaquin Vieira, who led the study to be published in the journal Nature. "The peak in the massive galaxies' formation was a billion years sooner than thought." Additional findings on the research will be published in the Astrophysical Journal.