A galaxy at a redshift z=6.96

When galaxy formation started in the history of the Universe remains unclear. Studies of the cosmic microwave background indicate that the Universe, after initial cooling ( following the Big Bang), was reheated and reionized by hot stars in newborn galaxies at a redshift in the range 6 < z < 14 ( ref. 1). Though several candidate galaxies at redshift z > 7 have been identified photometrically(2,3), galaxies with spectroscopically confirmed redshifts have been confined to z < 6.6 ( refs 4 - 8). Here we report a spectroscopic redshift of z = 6.96 ( corresponding to just 750 Myr after the Big Bang) for a galaxy whose spectrum clearly shows Lyman-alpha emission at 9,682 angstrom, indicating active star formation at a rate of similar to 10M(.) yr(-1), where M-. is the mass of the Sun. This demonstrates that galaxy formation was under way when the Universe was only similar to 6 per cent of its present age. The number density of galaxies at z approximate to 7 seems to be only 18 - 36 per cent of the density at z = 6.6.