Wilkinson Microwave Anisotropy Probe

NASA satellite used to survey the sky to map cosmic microwave background radiation (CMB). CMB is the residual radiation left over from the Big Bang and is thought to represent the oldest light in the universe. WMAP was launched on 30 June 2001, and achieved its permanent observing station in a semi-stable orbit around the L2 Lagrangian point. L2 lies 1.5 million km/932,100,000 mi from Earth (approximately four times further out than the Moon) on the far side of the Earth from the Sun, and moves with the Earth around the Sun. The WMAP mission is to measure the faint anisotropy, or variation in the temperature of the cosmic microwave background radiation, to enable the construction of a full sky map of the radiation. WMAP produced the first such map in April 2002. It is scheduled to continue observing until June 2007.

WMAP has been used to determine that the age of the universe is 13.7 billion years. WMAP data have also shown that the universe is composed of 4% normal matter, 23% of an unknown type of dark matter, and the remaining 73% of an unknown form of dark energy.

WMAP takes six months to accumulate the data required for a full sky map. The satellite was named after US cosmologist David Wilkinson, a pioneer in the concept of cosmic microwave background radiation and a member of the WMAP team.