This impressive crater is located on Ceres, the largest object in the asteroid belt between Mars and Jupiter. With a diameter of 950 km, Ceres has been considered, since 2006, a "dwarf planet", as Pluto. And, as this former ninth planet, it has also been visited for the first time by a spacecraft, in 2015. While the New Horizons mission sent back amazing views of Pluto (Picture of the Month, CERN Courier September 2015 p17 and November 2015 p17), NASA’s Dawn spacecraft was already in orbit around Ceres. Dawn’s camera has revealed more than 100 bright spots on the surface of Ceres. The brightest is in the 90 km-wide Occator Crater shown in this false-colour image combining near-infrared and visible observations. The mysterious spots are thought to be a type of salt – a magnesium sulphate called hexahydrate – rather than ice or snow, according to a new study published in Nature. An accompanying paper reports ammonia-rich clays, which are usually to be found in the outer solar system. Did Ceres migrate to the asteroid belt from a region near Neptune? Maybe. The solar system is still full of surprises and mysteries.