The European Space Agency's Planck satellite was a mission dedicated to studing the early Universe and its subsequent evolution by mapping the anisotropies in the cosmic microwave background (CMB) radiation. It was launched in May 2009 and scanned microwave and submillimetre sky until October 2013 producing high-resolution and high-sensitivity all-sky maps in nine frequency bands, from 30 to 857 GHz.

The main objective of the Planck mission was to measure the spatial anisotropies in the temperature of the CMB to an accuracy determined by fundamental astrophysical limits, by that obtaining virtually all the cosmological information encoded in the temperature anisotropies of the CMB. The satellite was also designed to measure to high accuracy the CMB polarisation anisotropies which provide not only a plenty of cosmological information but also yield a unique probe of the epoch of the Universe history when the first stars and galaxies formed. Lastly, Planck was the first submillimetre mission to map the entire sky to sub-Jansky sensitivity with resolution better than 10', thereby enabling to learn a wealth of information on the properties of extragalactic sources and on the dust and gas in our Galaxy.