http://arxiv.org/abs/astro-ph/0604050 Authors: Smadar Naoz (1), Shay Noter (1), Rennan Barkana (1) ((1) Tel Aviv University) Comments: 4 pages, 3 figures, submitted to PRL Large telescopes have allowed astronomers to observe galaxies that formed as early as 850 million years after the Big Bang. We predict when the first galaxy that astronomers can observe formed in the universe, accounting for the first time for the size of the universe and for three essential ingredients: the light travel time from distant galaxies, Poisson and density fluctuations on all scales, and the effect of very early cosmic history on galaxy formation. We find that the first observable star is most likely to have formed 30 million years after the Big Bang (at redshift 65), much earlier than previously expected. Also, the first galaxy as massive as our own Milky Way likely formed when the universe was only 400 Myr old. We also show that significant modifications are required in current methods of numerically simulating the formation of the first galaxies.