A space telescope launched by NASA in 2001 which measures the
temperature fluctuations in the
→ cosmic microwave background (CMB) radiation.
It creates a full-sky map of the CMB, with a 13 arcminute resolution
via multi-frequency observations. WMAP is the first mission to use a
→ Lagrangian point L2 as its permanent
observing station at a distance of 1.5 million km. WMAP completed its
prime two years of mission operations in September 2003 and is
continuing in 2009 its observations for still several years to come. WMAP’s
measurements have played a considerable role in establishing the current
standard model of cosmology. They are consistent with a Universe that is
dominated by → dark energy, with negative pressure or a
→ cosmological constant. In this model, the age of the Universe
is 13.73 ± 0.12 billion years. The current expansion rate of the Universe measured by
the Hubble constant, is 70.5 ± 1.3 km·s-1 Mpc-1.
The content of the Universe consists of 4.56% ± 0.15% ordinary
→ baryonic matter,
22.8% ± 1.3% → cold dark matter,
and 72.6% ± 1.5% of → dark energy,
that accelerates the → expansion of the Universe.
See also: WMAP, short for Wilkinson Microwave Anisotropy Probe, in
honor of David Todd Wilkinson (1935-2002), who had been a member of the mission’s
science team.
