This animation illustrates the painstaking work performed by cosmologists in the Planck Collaboration to extract the Cosmic Microwave Background from the data collected by Planck. The first image in the sequence shows the sources of emission detected on the whole sky at the microwave and sub-millimetre wavelengths probed by Planck, which range from 11.1 mm to 0.3 mm (corresponding to frequencies between 27 GHz and 1 THz).
The different sources of emission include:
– discrete emission from individual galactic and extragalactic sources;
– diffuse radio emission from interstellar material in the Milky Way, which is mostly due to synchrotron radiation emitted by electrons that spiral along the lines of the Galactic magnetic field, but also comprises bremsstrahlung radiation, emitted by electrons that are slowed down in the presence of protons, as well as emission from spinning dust grains;
– diffuse emission due to the thermal emission from interstellar dust in the Milky Way;
– and, finally, the Cosmic Microwave Background.
The cosmologists had to remove all possible contamination due to emission by foreground sources before they could fully explore the Cosmic Microwave Background data and compare them to cosmological models.