Every 405 thousand years, the Earth's orbit lengthens slightly due to the gravitational influence of Jupiter and Venus, which changes the planet's climate and affects the development of life on it, including leading to mass extinctions. This is the conclusion reached by scientists led by Dennis Kent (Dennis Kent) from Rutgers University. This was announced in a press release on EurekAlert !.
A cycle of 405 thousand years was predicted on the basis of calculations of the motion of the planets, but the results of theoretical modeling were reliable only for the last 50 million years. The relatively small increase in eccentricity (the degree of deviation from the circumference) of the Earth's orbit is also closely related to changes in the location of the planet's magnetic poles.
The researchers obtained more detailed data on changes in the direction of the Earth's magnetic field by analyzing sediments in the Newark Rift Basin, New Jersey, and sedimentary rocks in the Chinle Formation geological formation, Arizona. They recovered a core dating from the Late Triassic period between 253 and 202 million years ago. The samples contained zircon minerals interspersed with magnetite - a crystal by which one can judge the state of the planet's magnetic field.
The results obtained were consistent with theoretical calculations, which makes it possible to use the cycle for more accurate dating of events taking place on Earth, including the Triassic-Jurassic extinction, when a large number of animal species disappeared, freeing up ecological niches for dinosaurs.
