WMAP (Wilkinson Microwave Anisotropy Probe), previously known simply as MAP (Microwave Anisotropy Probe), is a NASA MIDEX satellite designed to map fluctuations in the cosmic microwave background over the whole sky with unprecedented accuracy and to provide insights into the formation of galaxies and the basic parameters of cosmology. WMAP's data bring into sharper focus the irregularities in the cosmic background discovered by COBE a decade earlier. The spacecraft operates from a halo orbit about the second Sun-Earth Lagrangian point, 1.5 million kilometers from Earth.