This animation illustrates the painstaking detective work performed by cosmologists in the Planck Collaboration to extract the cosmic microwave background from 15.5 months of data collected by Planck.

The first image in the sequence shows the sources of emission detected on the whole sky at the microwave and submillimetre 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 include discrete emission from individual galactic and extragalactic sources, and diffuse radio and thermal emission from interstellar material in the Milky Way.

The cosmologists had to remove all possible contamination due to emission by foreground sources before they could fully explore the cosmic microwave background, which is unveiled in the final slide of the animation.