Auroras are commonly seen in the north and south poles, but a disturbance in Earth's magnetic field about 41,000 years ago has sent auroras to unexpected parts of the world. The geomagnetic disruption called the Laschamp event, or the Laschamp excursion, has created auroras in the equator.
The event has tilted Earth's magnetic field on its axis, leading to the weakened magnetic pull in the north and south poles by a fraction of its former strength.
Disruption of Earth's Magnetic Field Sent Auroras Toward the Equator 41,000 Years Ago
What is Laschamp Event?
The Laschamp excursion was a geomagnetic event that caused a short reversal of the magnetic field of Earth 41,400 years ago at the end of the Last Glacial Period, according to Civils Today. Its name was derived from the village discovered in the French Massif Central.
The event is believed to have caused a series of catastrophic events, including electrical storms in the tropics, solar winds that generated auroras, Arctic air reaching the Americas, a surge of ice sheets and glaciers, and violent shifting of weather patterns.
Earth was exposed to high levels of ultraviolet during that time. Also, many giant animals called megafauna and Neanderthals may have gone extinct at that time while modern humans sought refuge inside the caves.
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Auroras Moving Towards the Equator
Science Alert reported that the magnetosphere's strength during the Laschamp event dropped to almost 4% of modern values and tilted on its side. Studies in the past predicted that the magnetosphere disappeared completely on Earth's dayside.
To prove this theory, researchers combined data from simulations of the interactions between the magnetosphere and the solar wind and fed those results to a model that calculated the location, shape, and strength of auroras in the past by analyzing the ionic pressure, density, and temperature.
They found that the magnetosphere shrank about 3.8 times the radius of Earth during the Laschamp event and never disappeared entirely. It affected the poles formerly positioned in the north and south to move towards the equatorial latitudes, and so did the auroras.
The strength of the Earth's magnetic field only returned to its original strength after 1,300 years. Previous studies have shown that the period of the Laschamp event may have shaped changes in Earth's atmosphere that affected habitability on prehistoric Earth as the planet was subjected to an environmental crisis.
First Humans in Australia May Have Witnessed Laschamp Event
A study, titled "Chronostratigraphy of a 270-Ka Sediment Record From Lake Selina, Tasmania: Combining Radiometric, Geomagnetic and Climatic Dating," published in Quaternary Geochronology, showed that the first humans that lived in Australia may have witnessed the Laschamp event over 41,000 years ago.
According to Science Daily, researchers drilled into a 270,000-year-old core from a Tasmanian lake and detected the record of the Laschamp event. Researchers noted that this is the first study since the 1980s.
They combined radiometric, geomagnetic, and climatic dating to reveal the details recorded in the core. They found that ancient humans living in Tasmania may have seen the spectacular auroras when Earth's magnetic field tilted when the north was south, and the south was north.
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