Planet consists mostly of planets the size of Neptune and smaller, down to smaller than Mercury. There are types of planets that do not exist in the Solar System: super-Earths and mini-Neptunes, which could be rocky like Earth or a mixture of volatiles and gas like Neptune—a radius of 1.75 times that of Earth is a possible dividing line between the two types of planet. There are hot Jupiters that orbit very close to their star and may evaporate to become chthonian planets, which are the leftover cores. Another possible type of planet is carbon planets, which form in systems with
Max Planck Institute for Solar System Research interactions with the solar wind, the atmospheric dynamics, or the generation of the terrestrial magnetic field by means of currents deep in the iron core of our planet. In addition, the Institute has along tradition in cometary research. A major highlight was the camera developed at the Institute for the ESA spacecraft Giotto which delivered the first photographs ever of a comet’s nucleus in 1986. A particular challenge was the development of numerous scientific instruments for the ESA Mission Rosetta, such as cameras, chemical analyzers, and essential components for the landing module Philae. Rosetta was launched in 2004, and matched