Figure 14-3 In Search of Primordial Photons (a) The Wilkinson Microwave Anisotropy Probe (WMAP) satellite, launched in 2001, improved upon the measurements of the spectrum and angular distribution of the cosmic microwave background taken by the COBE satellite. (b) The balloon-carried telescope BOOMERANG orbited above Antarctica for 10 days, collecting data used to resolve the cosmic microwave background, with 10 times higher resolution than that of COBE. All of these experiments found local temperature variations across the sky but no overall deviation from a blackbody spectrum.