APOD: 2003 December 31 - A Year of Resolving Cosmology
http://antwrp.gsfc.nasa.gov/apod/ap031231.html
http://antwrp.gsfc.nasa.gov/apod/ima...s_wmap_big.jpg

Explanation: This year, humanity learned that the universe is 13.7
billion years old. Before this year, the universe's age was thought to
be about 13 billion years, but really only constrained to be between
about 12 billion and 15 billion years old. The difference was made,
primarily, by a small satellite named the Wilkinson Microwave
Anisotropy Probe (WMAP) that had been collecting data in an unusual
Earth orbit. Pictured above is a sky map of the enabling data -- the
complete cosmic microwave background divided into two hemispheres, in
detail never before resolved, as recorded by the WMAP's first data
release. Besides universe age, new data and analyses of the spots on
the cosmic microwave background bolstered existing indications that the
universe is composed predominantly of a strange and mysterious type of
dark energy (73 percent). The remaining matter is only about 4 percent
in familiar atoms, with the remaining 23 percent in a somewhat
mysterious type of dark matter. During the year, much cosmological
research shifted from trying to find the parameters that define our
universe to trying to use these parameters as a tool for understanding
details of how our universe evolved.

See: http://antwrp.gsfc.nasa.gov/apod/ap031231.html