The Wilkinson Microwave Anisotropy Probe

The Wilkinson Microwave Anisotropy Probe (WMAP) has mapped the full sky in five frequency bands between 23 and 94 GHz. The primary goal of the mission is to produce high-fidelity, all-sky, polarization-sensitive maps that can be used to study the cosmic microwave background. Systematic errors in the maps are constrained to new levels: using all-sky data, aspects of the anisotropy may confidently be probed to sub-micron K levels. We give a brief description of the instrument and an overview of the first results from an analysis of maps made with one year of data. The highlights are (1) the flat ΛCDM model fits the data remarkably well, whereas an Einstein-de Sitter model does not; (2) we see evidence of the birth of the first generation of stars at z_r ≅20; (3) 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.