Definition of planet object can be irregular in shape, but beyond that point gravity begins to pull an object towards its own centre of mass until the object collapses into an ellipsoid. (None of the large objects of the Solar System are truly spherical. Many are spheroids, and several, such as the larger moons of Jupiter and Saturn and the dwarf planet , have been further distorted into ellipsoids by rapid rotation or tidal forces, but still in hydrostatic equilibrium.) However, there is no precise point at which an object can be said to have reached hydrostatic equilibrium. As Soter noted in his
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