Results from the first year of observations with the Wilkinson microwave anisotropy probe

The Wilkinson Microwave Anisotropy Probe (WMAP) has produced all-sky maps in five frequency bands between 23 and 94 GHz that can be used to study the CMB. We present an overview of the results from an analysis of maps made with one year of data. The highlights are that a) the flat ΛCDM model fits the data remarkably well, an Einstein-deSitter model (Ωtot = 1, Ω ^Λ=0) does not; b) from the polarization of the CMB there is evidence of the birth of the first generation of stars at zr ∼ 20; c) when the WMAP data are combined and compared with other cosmological probes a cosmic consistency emerges: multiple different lines of inquiry lead to the same results. The best-fit flat cosmological model to just the WMAP CMB data shows that the matter density is Ωm h ² = 0.14 -0.02 ^+0.02, the baryon density is Ω b h ² = 0.024 ± 0.001, and ns = 0.99 ± 0.04. WMAP continues to operate, and so results will improve.