Space Telescope Science
NASA's Hubble Space Telescope and Spitzer Space Telescope joined forces to discover and characterize four unusually bright galaxies as they appeared more than 13 billion years ago, just 500 million years after the big bang. Although Hubble has previously identified galaxies at this early epoch, astronomers were surprised to find objects that are about 10 to 20 times more luminous than anything seen previously.
The tiny galaxies are bursting with star formation activity, which accounts for their brilliance. The brightest one is forming stars approximately 50 times faster than the Milky Way does today. Although these fledgling galaxies are only one-twentieth the size of the Milky Way, they probably contain around a billion stars crammed together.