The Solar System consists of an inner region of small rocky planets and outer region of large giant planets. However, other planetary systems can have quite different architectures. Studies suggest that architectures of planetary systems are dependent on the conditions of their initial formation. Many systems with a hot Jupiter gas giant very close to the star have been found. Theories, such as planetary migration or scattering, have been proposed for the formation of large planets close to their parent stars. At present, few systems have been found to be analogous to the Solar System with terrestrial planets close to the parent star. More commonly, systems consisting of multiple Super-Earths have been detected.