The formation of the first stars and galaxies

Nature's series of review articles on astronomy, marking the International Year of Astronomy 2009, continues with a look at the 'final frontier' in observational astronomy: the formation of the first stars, galaxies and massive black holes. At present these objects can be studied only through simulations. Today's ground-based and space-borne telescopes have probed cosmic history back to a time and distance when the Universe was less than a tenth its present age. But the next generation of telescopes, with the latest theories as a benchmark, will be crossing the present high-redshift barrier to the first sources of light in the Universe.