41 thousand years ago auroras at the equator due to our magnetic field

During a geomagnetic perturbation that occurred 41,000 years ago and known as the Laschamp event or Laschamp excursion, our planet's magnetic north and south weakened and the magnetic field tilted on its axis, reducing to a fraction of its previous strength. This has diminished the magnetic attraction that normally directs the flow of high-energy solar particles to the north and south poles, where they interact with atmospheric gases to illuminate the night skies, creating the beautiful northern and southern lights.

It took about 1,300 years for the magnetic field to return to its original strength and inclination, and during that time the auroras drifted away to near-equatorial latitudes where they have typically never been seen, scientists said on Thursday, Dec. 16. at the American Geophysical Union (AGU) annual conference, held in New Orleans and online.

Agnit Mukhopadhyay, a graduate student in the Department of Climate and Space Sciences at the University of Michigan, at the AGU conference, explained that this period of intense geomagnetic change may also have shaped changes in the Earth's atmosphere, thus affecting living conditions in some parts ti of the planet.

The Earth's magnetic field arises from the agitation of the molten core of our planet and from the rotation of the planet, which generate magnetic poles on the surface to the north and south; magnetic field lines connect the poles in curved arcs, forming a protective zone, also known as the magnetosphere, which protects the planet from radioactive particles from space. The magnetosphere also protects the Earth's atmosphere from being consumed by the solar wind or by particles emitted by the Sun.

Mukhopadhyay and his colleagues used a concatenation of different models to discover this result. They first analyzed the planet's magnetism data from ancient rock sediments, as well as volcanic data, in a simulation of the magnetic field during the Laschamp event.



They combined these data with simulations of the interactions of the magnetosphere with the solar wind, then fed those results into another model that calculated the position, shape and strength of the aurora by analyzing the parameters of the solar particles that create the auroras, such as their pressure ionic, density and temperature.

This is the first time that scientists have used this technique "to simulate the geospatial system and predict magnetospheric configurations, along with the position of the aurora," said Mukhopadhyay.

The team found that although the magnetosphere shrank to about 3.8 times the Earth's radius during the Laschamp event, it never completely disappeared. During this period of reduced magnetic strength, the poles that were previously positioned north and south moved towards equatorial latitudes and the auroras followed.

Mukhopadhyay explained that “the geomagnetic tilt was significantly distorted by the geographic poles ". "This led to auroral precipitation following the magnetic poles and moving from the geographic polar regions of the Earth to the latitudes of the equator."

Previous studies have suggested that the Laschamps event could have influenced habitability on the Prehistoric earth plunging the planet into an environmental crisis, and new models have suggested that such an outcome was "highly probable."

Earlier this year, other researchers found that a weakened magnetosphere would be easily penetrated by solar winds, causing damage to the ozone layer, climatic upheavals and extinctions, possibly even contributing to the disappearance of Neanderthals in Europe, Live Science previously reported.

According to Mukhopadhyay, their findings do not demonstrate a cause-and-effect relationship between changes in the Laschamp magnetic field and severe ecological repercussions on Earth, the models offered insights for future research that could establish such a link.