Quasi-regular staying of solar system in supernova remnants and natural earth history

Abstract

The Solar system, oscillating relative the Galaxy midplane during its revolution around the Galactic center, can occasionally fall inside the gas-dust interstellar clouds, which include remnants of Supernova explosions. These are mainly accumulated in the vicinity of the Galactic midplane. Being the main sources of the cosmic rays, such remnants are characterized by a high density of relativistic particles. We show that the probability that the Earth meets a Supernova remnant in dangerous proximity during one of the Sun's passings through the Galaxy disk is about unity. Thus, the half-period, which slightly exceeds 30 million years, of the Solar system's oscillation near Galactic equator plane is a natural time unit for chronologization of global geological processes and phenomena in the Earth history. Astronomical and astrophysical data about the structure of the Galaxy, the type of Solar system motion in it, and proper data from radiobiology, gathered here, suggest and prove the statement that the quasi-regular encounters of the Solar system with Supernova remnants are the common cause of global biological catastrophes fatally affecting primarilyy the highest, most radiosensitive living organisms. The results obtained show that the continuous time span (about 1 billion years), needed for evolution of the simplest forms of life to the modern ones, during which the physical conditions on the Earth were approximately the same as the present ones, could not be realized. It is possible to restrict this time span by a few ten million years.