We have now entered a second 'golden age' of planetary exploration, with a host of exciting missions either underway, or due to report back in the next few years. Probes are able to land on planets or descend into their atmospheres, and apply powerful analytical techniques to determine their chemical compositions. The wealth of chemical information sent back from these missions has stimulated major efforts in laboratory experiments and computational modelling, and created a fascinating area for multidisciplinary exchange around the theme of the chemistry of the planets, encompassing aspects of chemistry (physical, organic and inorganic), physics and astronomy, geology and geochemistry, and exobiology, proving the right conditions for a fruitful Faraday Discussion at the interface of these disciplines. Furthermore, the recent discovery of water and methane in the atmosphere of an extrasolar planet (exoplanet) opens up a whole new and exciting field of planetary chemistry outside of the Solar System.