The mission improved on observations made by the NASAWilkinson Microwave Anisotropy Probe (WMAP). Planck provided a major source of information about cosmology and astrophysics. It tested theories of the early Universe and the origin of cosmic structure.
Since the end of its mission, Planck has made the most precise measurements of several key numbers. These include the average density of ordinary matter and dark matter in the Universe, and the age of the universe. Planck is now switched off.