The cosmogonical concept of the “Cosmogony of Open Solar System (COSS)” is discussed. Unlike the Kant–Laplace cosmogony, this concept takes into account the influence of processes in Galaxy on the formation and evolution of Solar System and its planets. Taking into account the phenomenon of jet outflow discovered in Galaxy, the COSS concept postulates that in history of Solar System development there were at least two main cycles of planet formation. At the first stage, presumably 6.6 billion years ago, the Sun and planets arose, and at the second stage 4.6 billion years ago, caused by destruction of planet Phaeton, the Solar System acquired its modern appearance. The adequacy of the two-stage formation of Solar System is substantiated by the agreed solution based on COSS concept to three problematic issues of cosmogony: (1) the origin of giant planets, (2) the nature of meteoritic matter, and (3) the formation of the Moon. In the modern cosmogony of Solar System, these issues are resolved independently and do not yet have a satisfactory explanation.