In 405,000-year cycles, the tug of nearby planets causes hotter summers, colder winters and drier droughts on our home planet
By Jason Daley
May 9, 2018
Astrologers have maintained for centuries that the position of the planets impact people’s personalities and emotions. And while this idea lacks scientific proof, it turns out that planetary alignments do affect some things on Earth. As George Dvorsky reports for Gizmodo, a new study presents the first physical evidence that the Venus’ and Jupiter’s gravity can cause shifts in Earth’s orbit—and swings in its climate—every 405,000 years.
Astronomers have long hypothesized that other planets in our solar system have impacts here on Earth, shifting its whirl around the sun from nearly circular to five percent elliptical. But they lacked much physical evidence of this process—and have long debated the particulars of the effects. The new study published in in the Proceedings of the National Academy of Sciences, demonstrates the influence of our planetary neighbor’s pull using a 1,500-foot rock core collected in 2013 from a butte in Arizona’s Petrified Forest National Park and cores from the site of ancient lake beds in New York and New Jersey.
Researchers noticed that lake sediment cores bear a regular pattern of ancient lakes drying up and refilling over the course of hundreds of thousands of years—a cycle that hints at cyclical changes in climate. However, they lacked the ability to precisely date those climatic shifts. The Arizona core, however, contain layers of ash from volcanic eruptions that could be dated because it contains radioisotopes.
The researchers aligned the Arizona core dates to the ancient lake cores using bands found in all of the cores, marking reversals in Earth’s magnetic fields. This allowed them to compare the records. The analysis demonstrated that the climate swings took place every 405,000 years for at least the last 215 million years, or through the Late Triassic age when dinosaurs roamed the Earth.
So why are Venus and Jupiter so influential on our orbit? Venus’s tug is so strong because it’s our closest planetary neighbor, approaching as close as 24 million miles. The sheer size of Jupiter—which is roughly 318 times as massive as Earth—means it also has an outsized pull on our planet. At the peak of that warped orbit, Earth undergoes hotter summers, colder winters as well as more intense periods of drought and wetness.
Knowing how this cycle works could impact on our understanding of past climate change and the arrival and disappearance of plant and animal species. “Scientists can now link changes in the climate, environment, dinosaurs, mammals and fossils around the world to this 405,000-year cycle in a very precise way,” lead author Dennis Kent, an expert in paleomagnetism at Columbia University and Rutgers tells Doyle Rice at USA Today. “The climate cycles are directly related to how the Earth orbits the sun and slight variations in sunlight reaching Earth lead to climate and ecological changes.”
The study is also important for the way the researchers dated the cores and presented a timeline of the geologic past, according to Steve Brusatte, a paleontologist at the University of Edinburgh, who was not involved in the work. In his discussion with Dvorsky, he calls the study “a tremendous piece of work.”
“It is a really important study for clarifying the Triassic timescale and untangling the sequence of events that occurred as Pangea began to split up and the dinosaurs originated and then diversified,” he tells Dvorsky. “It’s mostly a study of how to tell geological time rather than of how changes in climate relate to evolution.”
But the big question for most people is: Where are we currently on the Venus-Jupiter climate cycle and could their neighborly tug explain some of the changes in our climate? In a press release, Kent says we’re likely in the middle of the cycle when Earth’s orbit is almost circular. This means the swing is not causing climate disruptions. It’s most likely that any changes we are experiencing comes from outsized human input in the release of greenhouse gasses.
∫∫∫ And of course at the end it just HAD to be mentioned that “but what we’re experiencing now is HUMAN induced climate change.”