Sky map pixelization
WMAP makes sky maps in the "HEALPix" format of sphere pixelization developed by Gorski, Wandelt, and Hivon. A suite of Fortran and IDL software tools for working with HEALPix format maps is available from the HEALPix web site.
The HEALPix format allows the division of a sphere into finer and finer resolution patches of equal area.
Below (left) is an Earth topography map composed of 3,145,728 pixels (~7 arcmin resolution) and the second (right) is a model of the Cosmic Microwave Background (CMB) radiation temperature anisotropy, composed of 12,582,912 pixels (~3.4 arcmin resolution).