  The ESA's Planck satellite, dedicated to studying the early Universe and its
subsequent evolution, was launched 14 May 2009 and has been scanning the
microwave and submillimetre sky continuously since 12 August 2009. This paper
gives an overview of the mission and its performance, the processing, analysis,
and characteristics of the data, the scientific results, and the science data
products and papers in the release. The science products include maps of the
CMB and diffuse extragalactic foregrounds, a catalogue of compact Galactic and
extragalactic sources, and a list of sources detected through the SZ effect.
The likelihood code used to assess cosmological models against the Planck data
and a lensing likelihood are described. Scientific results include robust
support for the standard six-parameter LCDM model of cosmology and improved
measurements of its parameters, including a highly significant deviation from
scale invariance of the primordial power spectrum. The Planck values for these
parameters and others derived from them are significantly different from those
previously determined. Several large-scale anomalies in the temperature
distribution of the CMB, first detected by WMAP, are confirmed with higher
confidence. Planck sets new limits on the number and mass of neutrinos, and has
measured gravitational lensing of CMB anisotropies at greater than 25 sigma.
Planck finds no evidence for non-Gaussianity in the CMB. Planck's results agree
well with results from the measurements of baryon acoustic oscillations. Planck
finds a lower Hubble constant than found in some more local measures. Some
tension is also present between the amplitude of matter fluctuations derived
from CMB data and that derived from SZ data. The Planck and WMAP power spectra
are offset from each other by an average level of about 2% around the first
acoustic peak.
