The Earth’s orbit changes every 405 thousand years, say geologists

Gravitational interactions with Jupiter and Venus cause the Earth’s orbit to contract and stretch every 405 thousand years for more than 215 million years, geologists have found out.

“This is a startling discovery – we suspected that this cycle could have existed for about 50 million years, but we found out that it has been operating for at least 215 million years.” Now we can link and clarify the time when various climate changes took place, massive extinction, dinosaurs, mammals and other animals have appeared and disappeared, “said Dennis Kent of Rutgers University, USA.

Today, the Earth revolves around the Sun along a slightly elongated orbit that is almost 150 million kilometers away from the sun. Its perihelion – the closest point to the Sun – is about 5 million kilometers closer to the star than the aphelion, the farthest point. Thanks to this, winters in the southern hemisphere are slightly more severe than in the northern half, and summer – more hot.

In the past, scientists believe, the Earth’s orbit could be more elongated, which could dramatically change the climate of the planet, making it more extreme, and also causing extinctions and large-scale restructuring of ecosystems. Similar changes, as calculations of geologists and astrophysicists show, should have occurred as a result of the interaction of our planet with Jupiter and other gas giants.

About two decades ago, as Kent observes, he noted that the gravitational interactions of Jupiter, Earth and Venus had to change the orbit of our planet in a special way, compressing or stretching it by about 1% every 405 thousand years. His calculations showed that such a cycle of change of orbits should be extremely stable and it should have existed at least since the Cenozoic times.

Such unusual properties of this cycle, as well as the absence of other long-term oscillations of the orbit, forced Kent and his colleagues to search for their possible traces in the Earth’s rocks, in which the traces of the planet’s magnetic field imprisoned in crystals of iron-bearing rocks are often “imprinted”.

Five years ago, the authors of the article conducted excavations in Arizona, where the rocks formed approximately 215-210 million years ago, at the end of the Triassic period. At that time, the first ancestors of dinosaurs began to appear on Earth, and the reptiles and two-legged “mega-crocs” two meters tall began to gradually die out.

In these rocks, they managed to find a whole layer of volcanic ash and other igneous rocks, half a kilometer long, in which traces of the shifts of the magnetic axis of the planet have been preserved. Analyzing them, the geologists realized that they are dealing with the same orbital cycle of 405 thousand years.

This cycle, according to Kent and his colleagues, had an unusual effect on the climate of the planet at that time. In those times when the Earth’s orbit was stretching as far as possible, the level of precipitation in the territory of the future North America increased noticeably, and in the epoch of the “round” orbit it was noticeably smaller. This, according to scientists, should have influenced the evolution of the life and geology of our planet quite strongly.

Now the Earth, as scientists say, is in the “round” phase of this cycle. Its influence, on the other hand, on the climate of the planet in the short term will be minimal, as the current CO2 emissions and shorter and bright cycles of Milankovitch, associated with the “rocking” of the Earth’s rotation axis, affect temperatures much more strongly, and therefore similar “shifts of orbits “do not cause serious concern.