Listen to the terrifying sound of changes in the Earth 41,000 years ago
SCIENCE: A fascinating new video shows how Earth’s magnetic field messed up and almost completely disappeared during our planet’s most recent “polar reversal event,” about 41,000 years ago. An eerie soundscape of “alien-like” creaking sounds illustrates the strain put on our planet’s invisible protective shield. Earth’s magnetic field, or magnetosphere, first formed 3.7 billion years ago and is generated by a metallic ocean swirling within our planet’s outer core. The bubble of magnetism protects life on Earth from solar radiation and high-energy cosmic rays. Every so often, however, Earth’s internal dynamo weakens, causing the planet’s magnetic poles to swap.
The last time this happened was about 41,000 years ago, when the magnetosphere suddenly weakened and reversed a few times over the course of several centuries. Evidence of this geomagnetic excursion, known as the Laschamp event, can be found in ancient lava flows, which contain unusually high proportions of certain isotopes due to increased levels of cosmic rays. Previous research on fossil tree rings also showed that the magnetosphere was reduced to about 5% of its current strength, enabling solar radiation to paint aurorae across the equator.
The new video, released by the European Space Agency (ESA) on October 10, shows how magnetic-field lines within the magnetosphere were distorted and weakened during the Laschamp event. The animation, which covers about 3,000 years, was created using data from ESA’s Swarm mission, a trio of satellites that have been monitoring the magnetosphere since 2013. The data also helped researchers create a disturbing “soundscape” to accompany the footage, which emphasizes the enormous pressure exerted on the magnetosphere during the event.
“The process of transforming sounds with data is similar to creating music from a score,” the researchers wrote in a statement. But instead of using musical instruments, the team used recordings of natural sounds, such as wood creaking and rocks falling, to create the strange “alien-like sounds.” According to the ESA, the same research team previously created another soundscape using similar techniques, showing how the magnetosphere has changed over the past 100,000 years.
