Sketched out in 1992, selected by ESA in 1996, and launched in 2009, the Planck satellite was shut off in 2013, after a measuring stage of the mission that collected over a trillion samples and exceeded all expectations. The Planck collaboration delivered a first set of cosmological data and results in March 21st 2013, and the full set in February 2015. Part of the data delivery is a “definitive” map of the anisotropies of the Cosmic Microwave Background (CMB), its angular power spectrum together with its full statistical characterisation, and the implications for cosmology. The 2015 delivery further includes pioneering polarisation maps, spectra, and their analyses.
The temperature anisotropy map displays minuscule variations as a function of the observing direction, of rms ~100microK, of the fossil radiation around its mean temperature of 2.725K. Other maps reveal the CMB polarisation patterns. These anisotropies are the imprint of the primordial fluctuations which initiated the growth of the large scale structures of the Universe, as transformed by their evolution, in particular during the first 370 000 years. These anisotropies can then be confronted with theoretical expectations.
I will described the results we obtained so far, both in terms of content of the universe and of characteristics of the primordial fluctuations which are found to match very well with expectations from an early inflationary phase in a Universe filled with cold dark matter and whose expansion recently started to accelerate.
