Illustration of the Planck space observatory at the centre of a globe showing anisotropies of the cosmic microwave background (CMB). This unmanned spacecraft was launched on 14th May 2009. It travelled to the second Lagrangian point (L2), situated about 1.5 million kilometres from Earth in the direction opposite to the Sun. The aim of the mission was to study the Cosmic Microwave Background, the radiation left over from the Big Bang. Planck took around 6 months to arrive, and then spent 15 months surveying the sky. Following excellent initial results, the mission was extended, with observations continuing to the end of 2013.